Method for transmitting and receiving phase tracking reference signal in wireless communication system, and apparatus therefor

ABSTRACT

Disclosed are a method for transmitting and receiving a phase tracking reference signal (PTRS) in a wireless communication system, and an apparatus therefor. Particularly, a method for receiving a phase tracking reference signal (PTRS) by a user equipment (UE) in a wireless communication system may include the steps of: receiving PTRS configuration information, wherein the PTRS configuration information includes information on a frequency density of a PTRS; receiving downlink control information (DCI), wherein a plurality of TCI states are indicated on the basis of the DCI; and receiving the PTRS, wherein on the basis that resources in a frequency domain associated with each TCI state of the plurality of TCI states do not overlap with each other, the frequency density of the PTRS is determined by the number of resource blocks associated with each TCI state.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. § 119(e) this application is a continuation ofInternational Application No. PCT/KR2020/013501, filed on Oct. 5, 2020,which claims the benefit of Korean Application No. 10-2019-0122731,filed on Oct. 3, 2019, and Korean Application No. 10-2019-0143014, filedon Nov. 8, 2019, the contents of which are all hereby incorporated byreference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system, andmore particularly to a method of transmitting and receiving a phasetracking reference signal (PTRS) considering joint transmission ofmultiple transmission reception points (TRPs) and a device supportingthe same.

BACKGROUND ART

Mobile communication systems have been developed to provide a voiceservice while ensuring the activity of a user. However, in the mobilecommunication system, not only a voice, but also a data service isextended. At present, there is a shortage of resources due to anexplosive increase in traffic, and users demand a higher speed service.As a result, a more advanced mobile communication system is required.

Requirements for a next-generation mobile communication system should beable to support the acceptance of explosive data traffic, a dramaticincrease in the per-user data rate, the acceptance of a significantincrease in the number of connected devices, very low end-to-endlatency, and high-energy efficiency. To this end, various technologiesare researched, which include dual connectivity, massive multiple inputmultiple output (MIMO), in-band full duplex, non-orthogonal multipleaccess (NOMA), super wideband support, device networking, and the like.

SUMMARY

The present disclosure provides a method of transmitting and receiving,by a user equipment (UE) supported by multiple transmission receptionpoints (TRPs), a phase tracking reference signal (PTRS) in a wirelesscommunication system.

More specifically, the present disclosure provides a method ofallocating time/frequency resources for each TRP considering single DCIbased M-TRP transmission.

The present disclosure also provides a method of determining a referenceresource size for calculating a size of a transport block transmittedfrom each TRP considering single DCI based M-TRP transmission.

The present disclosure also provides a method of determining a frequencydensity of a PTRS considering M-TRP transmission.

The present disclosure also provides a resource mapping method oftransmitting a PTRS in time/frequency resources allocated for each TRP.

The technical objects to be achieved by the present disclosure are notlimited to those that have been described hereinabove merely by way ofexample, and other technical objects that are not mentioned can beclearly understood from the following descriptions by those skilled inthe art, to which the present disclosure pertains.

In one aspect of the present disclosure, there is provided a method ofreceiving, by a user equipment (UE), a phase tracking reference signal(PTRS) in a wireless communication system, the method comprisingreceiving PTRS configuration information, wherein the PTRS configurationinformation includes information for a frequency density of the PTRS;receiving downlink control information (DCI), wherein a plurality of TCIstates are indicated based on the DCI; and receiving the PTRS, whereinbased on non-overlapping resources in a frequency domain related to eachTCI state of the plurality of TCI states, the frequency density of thePTRS is determined by a number of resource blocks related to each TCIstate.

The information for the frequency density of the PTRS may include afirst threshold and a second threshold. The frequency density of thePTRS may be determined by comparing (i) the number of resource blocksrelated to each TCI state and (ii) at least one of the first thresholdor the second threshold.

Each of the first threshold and the second threshold may be set as aplurality of values.

The DCI may include a frequency resource assignment field, and theplurality of TCI states may be mapped to a frequency resource domainassigned based on the frequency resource assignment field.

The assigned frequency resource domain may include a first region and asecond region that do not overlap in the frequency domain. The firstregion may be related to a first TCI state, and a second region may berelated to a second TCI state.

The assigned frequency resource domain may be divided into the firstregion including an even-numbered precoding resource block group (PRG)and the second region including an odd-numbered PRG.

The assigned frequency resource domain may be divided into the firstregion and the second region that do not overlap based on a floorfunction.

A first frequency density of the PTRS may be determined by a number ofresource blocks of the first region, and a second frequency density ofthe PTRS may be determined by a number of resource blocks of the secondregion.

In the first region, the PTRS may be mapped to a resource element basedon the first frequency density. In the second region, the PTRS may bemapped to a resource element based on the second frequency density.

The DCI may include an antenna port field, and DM-RS ports of the sameCDM group may be indicated based on the antenna port field.

In another aspect of the present disclosure, there is provided a userequipment (UE) receiving a phase tracking reference signal (PTRS) in awireless communication system, the UE comprising one or moretransceivers; one or more processors; and one or more memoriesconfigured to store instructions for operations executed by the one ormore processors, the one or more memories being connected to the one ormore processors, wherein the operations comprise receiving PTRSconfiguration information, wherein the PTRS configuration informationincludes information for a frequency density of the PTRS; receivingdownlink control information (DCI); wherein a plurality of TCI statesare indicated based on the DCI; and receiving the PTRS, wherein based onnon-overlapping resources in a frequency domain related to each TCIstate of the plurality of TCI states, the frequency density of the PTRSis determined by a number of resource blocks related to each TCI state.

In another aspect of the present disclosure, there is provided a methodof transmitting, by a base station (BS), a phase tracking referencesignal (PTRS) in a wireless communication system, the method comprisingtransmitting, to a user equipment (UE), PTRS configuration information,wherein the PTRS configuration information includes information for afrequency density of the PTRS; transmitting, to the UE, downlink controlinformation (DCI); wherein a plurality of TCI states are indicated basedon the DCI; and transmitting, to the UE, the PTRS, wherein based onnon-overlapping resources in a frequency domain related to each TCIstate of the plurality of TCI states, the frequency density of the PTRSis determined by a number of resource blocks related to each TCI state.

In another aspect of the present disclosure, there is provided a basestation (BS) transmitting a phase tracking reference signal (PTRS) in awireless communication system, the base station comprising one or moretransceivers; one or more processors; and one or more memoriesconfigured to store instructions for operations executed by the one ormore processors, the one or more memories being connected to the one ormore processors, wherein the operations comprise transmitting, to a userequipment (UE), PTRS configuration information, wherein the PTRSconfiguration information includes information for a frequency densityof the PTRS; transmitting, to the UE, downlink control information(DCI); wherein a plurality of TCI states are indicated based on the DCI;and transmitting, to the UE, the PTRS, wherein based on non-overlappingresources in a frequency domain related to each TCI state of theplurality of TCI states, the frequency density of the PTRS is determinedby a number of resource blocks related to each TCI state.

In another aspect of the present disclosure, there is provided a devicecomprising one or more memories; and one or more processors operativelyconnected to the one or more memories, wherein the one or moreprocessors are configured to allow the device to receive PTRSconfiguration information, receive downlink control information (DCI),and receive the PTRS, wherein the PTRS configuration informationincludes information for a frequency density of the PTRS, wherein aplurality of TCI states are indicated based on the DCI, and whereinbased on non-overlapping resources in a frequency domain related to eachTCI state of the plurality of TCI states, the frequency density of thePTRS is determined by a number of resource blocks related to each TCIstate.

In another aspect of the present disclosure, there is provided one ormore non-transitory computer readable mediums storing one or moreinstructions, wherein the one or more instructions executable by one ormore processors allow a user equipment (UE) to receive PTRSconfiguration information, receive downlink control information (DCI),and receive the PTRS, wherein the PTRS configuration informationincludes information for a frequency density of the PTRS, wherein aplurality of TCI states are indicated based on the DCI, and whereinbased on non-overlapping resources in a frequency domain related to eachTCI state of the plurality of TCI states, the frequency density of thePTRS is determined by a number of resource blocks related to each TCIstate.

Embodiments of the present disclosure can transmit and receive a phasetracking reference signal (PTRS) based on multiple transmissionreception points (TRPs).

Embodiments of the present disclosure can determine time/frequencyresources for each TRP based on time/frequency resources configured viaDCI in single DCI based M-TRP transmission. Embodiments of the presentdisclosure can also determine a reference resource size for calculatinga size of a transport block transmitted from each TRP.

Embodiments of the present disclosure can configure optimization of afrequency density of a PTRS considering M-TRP transmission. Embodimentsof the present disclosure can also transmit and receive a PTRS mapped toa resource element based on a determined frequency density.

Effects which may be obtained from the present disclosure are notlimited by the above effects, and other effects that have not beenmentioned may be clearly understood from the following description bythose skilled in the art to which the present disclosure pertains.

DESCRIPTION OF DRAWINGS

The accompany drawings, which are included to provide a furtherunderstanding of the present disclosure and are incorporated on andconstitute a part of this specification illustrate embodiments of thepresent disclosure and together with the description serve to explainthe principles of the present disclosure.

FIG. 1 is a diagram illustrating an example of an overall systemstructure of NR to which a method proposed in the present disclosure maybe applied.

FIG. 2 illustrates a relationship between an uplink frame and a downlinkframe in a wireless communication system to which a method proposed inthe present disclosure may be applied.

FIG. 3 illustrates an example of a frame structure in an NR system.

FIG. 4 illustrates an example of a resource grid supported by a wirelesscommunication system to which a method proposed in the presentdisclosure may be applied.

FIG. 5 illustrates examples of a resource grid for each antenna port andnumerology to which a method proposed in the present disclosure may beapplied.

FIG. 6 illustrates physical channels and general signal transmission inused in 3GPP system.

FIG. 7 illustrates an example of a downlink transmission/receptionoperation.

FIG. 8 illustrates an example of an uplink transmission/receptionoperation.

FIG. 9 is a flow chart illustrating an example of a DL DMRS procedure.

FIGS. 10A and 10B illustrate an example of a transmission/receptionmethod for improving reliability using transmission in multiple TRPs.

FIGS. 11A and 11B illustrate an example of transmitting data to a UEusing different frequency resources at different TRPs.

FIGS. 12A and 12B illustrate an example of a method of allocatingfrequency resources to different TRPs via single DCI in a single DCIbased M-TRP operation.

FIG. 13 illustrates an example of allocating a frequency resource toeach TRP based on a PRG set.

FIG. 14 illustrates an example of defining a PRG set based on a BWP onwhich a PDSCH can be transmitted, and a mapping relationship between thePRG set and a TCI state in accordance with methods described in thepresent disclosure.

FIG. 15 illustrates an example of a method of mapping a TCI staterelated to each TRP according to a resource allocation method of afrequency domain for a PDSCH.

FIG. 16 is a flow chart illustrating an example of a DL PTRS procedure.

FIG. 17 illustrates an example of a mapping relationship betweenscheduled RBs and a TCI state corresponding to each TRP and an exampleof RBs on which PTRS is transmitted, when precoding granularity isconfigured as 2 in a frequency domain and a PRG set includes one PRG.

FIG. 18 illustrates an example of a method of determining a frequencyresource of M-TRP based on a frequency resource indicated via DCIaccording to methods described in the present disclosure.

FIG. 19 illustrates an example of signaling between a UE and a networkside in a single DCI based M-TRP transmission to which methods and/orembodiments described in the present disclosure are applicable.

FIG. 20 illustrates an example of an operation flow chart of a UEreceiving a PTRS to which methods and/or embodiments described in thepresent disclosure are applicable.

FIG. 21 illustrates an example of an operation flow chart of a basestation transmitting a PTRS to which methods and/or embodimentsdescribed in the present disclosure are applicable.

FIG. 22 illustrates a communication system 1 applied to the presentdisclosure.

FIG. 23 illustrates a wireless device which may be applied to thepresent disclosure.

FIG. 24 illustrates a signal processing circuit for a transmit signal.

FIG. 25 illustrates another example of a wireless device applied to thepresent disclosure.

FIG. 26 illustrates a portable device applied to the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings. A detailed description to be disclosed below together with theaccompanying drawing is to describe exemplary embodiments of the presentdisclosure and not to describe a unique embodiment for carrying out thepresent disclosure. The detailed description below includes details toprovide a complete understanding of the present disclosure. However,those skilled in the art know that the present disclosure may be carriedout without the details.

In some cases, in order to prevent a concept of the present disclosurefrom being ambiguous, known structures and devices may be omitted orillustrated in a block diagram format based on core functions of eachstructure and device.

Hereinafter, downlink (DL) means communication from the base station tothe terminal and uplink (UL) means communication from the terminal tothe base station. In downlink, a transmitter may be part of the basestation, and a receiver may be part of the terminal. In uplink, thetransmitter may be part of the terminal and the receiver may be part ofthe base station. The base station may be expressed as a firstcommunication device and the terminal may be expressed as a secondcommunication device. A base station (BS) may be replaced with termsincluding a fixed station, a Node B, an evolved-NodeB (eNB), a NextGeneration NodeB (gNB), a base transceiver system (BTS), an access point(AP), a network (5G network), an AI system, a road side unit (RSU), avehicle, a robot, an Unmanned Aerial Vehicle (UAV), an Augmented Reality(AR) device, a Virtual Reality (VR) device, and the like. Further, theterminal may be fixed or mobile and may be replaced with terms includinga User Equipment (UE), a Mobile Station (MS), a user terminal (UT), aMobile Subscriber Station (MSS), a Subscriber Station (SS), an AdvancedMobile Station (AMS), a Wireless Terminal (WT), a Machine-TypeCommunication (MTC) device, a Machine-to-Machine (M2M) device, and aDevice-to-Device (D2D) device, the vehicle, the robot, an AI module, theUnmanned Aerial Vehicle (UAV), the Augmented Reality (AR) device, theVirtual Reality (VR) device, and the like.

The following technology may be used in various radio access systemincluding CDMA, FDMA, TDMA, OFDMA, SC-FDMA, and the like. The CDMA maybe implemented as radio technology such as Universal Terrestrial RadioAccess (UTRA) or CDMA2000. The TDMA may be implemented as radiotechnology such as a global system for mobile communications(GSM)/general packet radio service (GPRS)/enhanced data rates for GSMevolution (EDGE). The OFDMA may be implemented as radio technology suchas Institute of Electrical and Electronics Engineers (IEEE) 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Evolved UTRA (E-UTRA), or thelike. The UTRA is a part of Universal Mobile Telecommunications System(UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution(LTE) is a part of Evolved UMTS (E-UMTS) using the E-UTRA andLTE-Advanced (A)/LTE-A pro is an evolved version of the 3GPP LTE. 3GPPNR (New Radio or New Radio Access Technology) is an evolved version ofthe 3GPP LTE/LTE-A/LTE-A pro.

For clarity of description, the technical spirit of the presentdisclosure is described based on the 3GPP communication system (e.g.,LTE-A or NR), but the technical spirit of the present disclosure are notlimited thereto. LTE means technology after 3GPP TS 36.xxx Release 8. Indetail, LTE technology after 3GPP TS 36.xxx Release 10 is referred to asthe LTE-A and LTE technology after 3GPP TS 36.xxx Release 13 is referredto as the LTE-A pro. The 3GPP NR means technology after TS 38.xxxRelease 15. The LTE/NR may be referred to as a 3GPP system. “xxx” meansa detailed standard document number. The LTE/NR may be collectivelyreferred to as the 3GPP system. Matters disclosed in a standard documentopened before the present disclosure may be referred to for a backgroundart, terms, omissions, etc., used for describing the present disclosure.For example, the following documents may be referred to.

3GPP LTE

-   -   36.211: Physical channels and modulation    -   36.212: Multiplexing and channel coding    -   36.213: Physical layer procedures    -   36.300: Overall description    -   36.331: Radio Resource Control (RRC)

3GPP NR

-   -   38.211: Physical channels and modulation    -   38.212: Multiplexing and channel coding    -   38.213: Physical layer procedures for control    -   38.214: Physical layer procedures for data    -   38.300: NR and NG-RAN Overall Description    -   36.331: Radio Resource Control (RRC) protocol specification

As more and more communication devices require larger communicationcapacity, there is a need for improved mobile broadband communicationcompared to the existing radio access technology (RAT). Further, massivemachine type communications (MTCs), which provide various servicesanytime and anywhere by connecting many devices and objects, are one ofthe major issues to be considered in the next generation communication.In addition, a communication system design considering a service/UEsensitive to reliability and latency is being discussed. Theintroduction of next generation radio access technology consideringenhanced mobile broadband communication (eMBB), massive MTC (mMTC),ultra-reliable and low latency communication (URLLC) is discussed, andin the present disclosure, the technology is called new RAT forconvenience. The NR is an expression representing an example of 5G radioaccess technology (RAT).

Three major requirement areas of 5G include (1) an enhanced mobilebroadband (eMBB) area, (2) a massive machine type communication (mMTC)area and (3) an ultra-reliable and low latency communications (URLLC)area.

Some use cases may require multiple areas for optimization, and otheruse case may be focused on only one key performance indicator (KPI). 5Gsupport such various use cases in a flexible and reliable manner.

eMBB is far above basic mobile Internet access and covers media andentertainment applications in abundant bidirectional tasks, cloud oraugmented reality. Data is one of key motive powers of 5G, and dedicatedvoice services may not be first seen in the 5G era. In 5G, it isexpected that voice will be processed as an application program using adata connection simply provided by a communication system. Major causesfor an increased traffic volume include an increase in the content sizeand an increase in the number of applications that require a high datatransfer rate. Streaming service (audio and video), dialogue type videoand mobile Internet connections will be used more widely as more devicesare connected to the Internet. Such many application programs requireconnectivity always turned on in order to push real-time information andnotification to a user. A cloud storage and application suddenlyincreases in the mobile communication platform, and this may be appliedto both business and entertainment. Furthermore, cloud storage is aspecial use case that tows the growth of an uplink data transfer rate.5G is also used for remote business of cloud. When a tactile interfaceis used, further lower end-to-end latency is required to maintainexcellent user experiences. Entertainment, for example, cloud game andvideo streaming are other key elements which increase a need for themobile broadband ability. Entertainment is essential in the smartphoneand tablet anywhere including high mobility environments, such as atrain, a vehicle and an airplane. Another use case is augmented realityand information search for entertainment. In this case, augmentedreality requires very low latency and an instant amount of data.

Furthermore, one of the most expected 5G use case relates to a functioncapable of smoothly connecting embedded sensors in all fields, that is,mMTC. Until 2020, it is expected that potential IoT devices will reach20.4 billions. The industry IoT is one of areas in which 5G performsmajor roles enabling smart city, asset tracking, smart utility,agriculture and security infra.

URLLC includes a new service which will change the industry throughremote control of major infra and a link having ultra-reliability/lowavailable latency, such as a self-driving vehicle. A level ofreliability and latency is essential for smart grid control, industryautomation, robot engineering, drone control and adjustment.

Multiple use cases are described more specifically.

5G may supplement fiber-to-the-home (FTTH) and cable-based broadband (orDOCSIS) as means for providing a stream evaluated from gigabits persecond to several hundreds of mega bits per second. Such fast speed isnecessary to deliver TV with resolution of 4K or more (6K, 8K or more)in addition to virtual reality and augmented reality. Virtual reality(VR) and augmented reality (AR) applications include immersive sportsgames. A specific application program may require a special networkconfiguration. For example, in the case of VR game, in order for gamecompanies to minimize latency, a core server may need to be integratedwith the edge network server of a network operator.

An automotive is expected to be an important and new motive power in 5G,along with many use cases for the mobile communication of an automotive.For example, entertainment for a passenger requires a high capacity anda high mobility mobile broadband at the same time. The reason for thisis that future users continue to expect a high-quality connectionregardless of their location and speed. Another use example of theautomotive field is an augmented reality dashboard. The augmentedreality dashboard overlaps and displays information, identifying anobject in the dark and notifying a driver of the distance and movementof the object, over a thing seen by the driver through a front window.In the future, a wireless module enables communication betweenautomotives, information exchange between an automotive and a supportedinfrastructure, and information exchange between an automotive and otherconnected devices (e.g., devices accompanied by a pedestrian). A safetysystem guides alternative courses of a behavior so that a driver maydrive more safely, thereby reducing a danger of an accident. A next stepwill be a remotely controlled or self-driven vehicle. This requires veryreliable, very fast communication between different self-driven vehiclesand between an automotive and infra. In the future, a self-drivenvehicle may perform all driving activities, and a driver will be focusedon things other than traffic, which cannot be identified by anautomotive itself. Technical requirements of a self-driven vehiclerequire ultra-low latency and ultra-high speed reliability so thattraffic safety is increased up to a level which cannot be achieved by aperson.

A smart city and smart home mentioned as a smart society will beembedded as a high-density radio sensor network. The distributed networkof intelligent sensors will identify the cost of a city or home and acondition for energy-efficient maintenance. A similar configuration maybe performed for each home. All of a temperature sensor, a window andheating controller, a burglar alarm and home appliances are wirelesslyconnected. Many of such sensors are typically a low data transfer rate,low energy and a low cost. However, for example, real-time HD video maybe required for a specific type of device for surveillance.

The consumption and distribution of energy including heat or gas arehighly distributed and thus require automated control of a distributedsensor network. A smart grid collects information, and interconnectssuch sensors using digital information and a communication technology sothat the sensors operate based on the information. The information mayinclude the behaviors of a supplier and consumer, and thus the smartgrid may improve the distribution of fuel, such as electricity, in anefficient, reliable, economical, production-sustainable and automatedmanner. The smart grid may be considered to be another sensor networkhaving small latency.

A health part owns many application programs which reap the benefits ofmobile communication. A communication system may support remotetreatment providing clinical treatment at a distant place. This helps toreduce a barrier for the distance and may improve access to medicalservices which are not continuously used at remote farming areas.Furthermore, this is used to save life in important treatment and anemergency condition. A radio sensor network based on mobilecommunication may provide remote monitoring and sensors for parameters,such as the heart rate and blood pressure.

Radio and mobile communication becomes increasingly important in theindustry application field. Wiring requires a high installation andmaintenance cost. Accordingly, the possibility that a cable will bereplaced with reconfigurable radio links is an attractive opportunity inmany industrial fields. However, to achieve the possibility requiresthat a radio connection operates with latency, reliability and capacitysimilar to those of the cable and that management is simplified. Lowlatency and a low error probability is a new requirement for aconnection to 5G.

Logistics and freight tracking is an important use case for mobilecommunication, which enables the tracking inventory and packagesanywhere using a location-based information system. The logistics andfreight tracking use case typically requires a low data speed, but awide area and reliable location information.

In a new RAT system including NR uses an OFDM transmission scheme or asimilar transmission scheme thereto. The new RAT system may follow OFDMparameters different from OFDM parameters of LTE. Alternatively, the newRAT system may follow numerology of conventional LTE/LTE-A as it is orhave a larger system bandwidth (e.g., 100 MHz). Alternatively, one cellmay support a plurality of numerologies. In other words, UEs thatoperate with different numerologies may coexist in one cell.

The numerology corresponds to one subcarrier spacing in a frequencydomain. Different numerologies may be defined by scaling referencesubcarrier spacing to an integer N.

Definition of Terms

eLTE eNB: The eLTE eNB is the evolution of eNB that supportsconnectivity to EPC and NGC.

gNB: A node which supports the NR as well as connectivity to NGC.

New RAN: A radio access network which supports either NR or E-UTRA orinterfaces with the NGC.

Network slice: A network slice is a network created by the operatorcustomized to provide an optimized solution for a specific marketscenario which demands specific requirements with end-to-end scope.

Network function: A network function is a logical node within a networkinfrastructure that has well-defined external interfaces andwell-defined functional behavior.

NG-C: A control plane interface used on NG2 reference points between newRAN and NGC.

NG-U: A user plane interface used on NG3 references points between newRAN and NGC.

Non-standalone NR: A deployment configuration where the gNB requires anLTE eNB as an anchor for control plane connectivity to EPC, or requiresan eLTE eNB as an anchor for control plane connectivity to NGC.

Non-standalone E-UTRA: A deployment configuration where the eLTE eNBrequires a gNB as an anchor for control plane connectivity to NGC.

User plane gateway: A termination point of NG-U interface.

Overview of System

FIG. 1 illustrates an example of an overall structure of a NR system towhich a method proposed in the present disclosure is applicable.

Referring to FIG. 1 , an NG-RAN consists of gNBs that provide an NG-RAuser plane (new AS sublayer/PDCP/RLC/MAC/PHY) and control plane (RRC)protocol terminations for a user equipment (UE).

The gNBs are interconnected with each other by means of an Xn interface.

The gNBs are also connected to an NGC by means of an NG interface.

More specifically, the gNBs are connected to an access and mobilitymanagement function (AMF) by means of an N2 interface and to a userplane function (UPF) by means of an N3 interface.

New Rat (NR) Numerology and Frame Structure

In the NR system, multiple numerologies may be supported. Thenumerologies may be defined by subcarrier spacing and a CP (CyclicPrefix) overhead. Spacing between the plurality of subcarriers may bederived by scaling basic subcarrier spacing into an integer N (or μ). Inaddition, although a very low subcarrier spacing is assumed not to beused at a very high subcarrier frequency, a numerology to be used may beselected independent of a frequency band.

In addition, in the NR system, a variety of frame structures accordingto the multiple numerologies may be supported.

Hereinafter, an orthogonal frequency division multiplexing (OFDM)numerology and a frame structure, which may be considered in the NRsystem, will be described.

A plurality of OFDM numerologies supported in the NR system may bedefined as in Table 1.

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal, Extended 3 120 Normal 4 240 Normal

The NR supports multiple numerologies (or subcarrier spacing (SCS)) forsupporting various 5G services. For example, when the SCS is 15 kHz, awide area in traditional cellular bands is supported and when the SCS is30 kHz/60 kHz, dense-urban, lower latency, and wider carrier bandwidthare supported, and when the SCS is more than 60 kHz, a bandwidth largerthan 24.25 GHz is supported in order to overcome phase noise.

An NR frequency band is defined as frequency ranges of two types (FR1and FR2). FR1 and FR2 may be configured as shown in Table 2 below.Further, FR2 may mean a millimeter wave (mmW).

TABLE 2 Frequency Range Corresponding designation frequency rangeSubcarrier Spacing FR1  410 MHz-7125 MHz  15, 30, 60 kHz FR2 24250MHz-52600 MHz 60, 120, 240 kHz

Regarding a frame structure in the NR system, a size of various fieldsin the time domain is expressed as a multiple of a time unit ofT_(s)=1/(Δf_(max)·N_(f)). In this case, Δf_(max)=480·10³, andN_(f)=4096. DL and UL transmission is configured as a radio frame havinga section of T_(f)=(Δf_(max)·N_(f)/100)·T_(s)=10 ms. The radio frame iscomposed of ten subframes each having a section ofT_(f)=(Δf_(max)·N_(f)/100)·T_(s)=1 ms. In this case, there may be a setof UL frames and a set of DL frames.

FIG. 2 illustrates a relation between an uplink frame and a downlinkframe in a wireless communication system to which a method proposed inthe present disclosure is applicable.

As illustrated in FIG. 2 , uplink frame number i for transmission from auser equipment (UE) shall start T_(TA)=N_(TA)T_(s) before the start of acorresponding downlink frame at the corresponding UE.

Regarding the numerology μ, slots are numbered in increasing order ofn_(s) ^(μ)∈{0, . . . , N_(subframe) ^(slots,μ)−1} within a subframe andare numbered in increasing order of n_(s,f) ^(μ)∈{0, . . . ,N_(subframe) ^(slots,μ)−1} within a radio frame. One slot consists ofconsecutive OFDM symbols of N_(symb) ^(μ), and N_(symb) ^(μ) isdetermined depending on a numerology used and slot configuration. Thestart of slots n_(s) ^(μ) in a subframe is aligned in time with thestart of OFDM symbols n_(s) ^(μ)N_(symb) ^(μ) in the same subframe.

Not all UEs are able to transmit and receive at the same time, and thismeans that not all OFDM symbols in a downlink slot or an uplink slot areavailable to be used.

Table 3 represents the number N_(symb) ^(slot) of OFDM symbols per slot,the number N_(slot) ^(frame,μ) slot of slots per radio frame, and thenumber N_(slot) ^(subframe,μ) of slots per subframe in a normal CP.Table 4 represents the number of OFDM symbols per slot, the number ofslots per radio frame, and the number of slots per subframe in anextended CP.

TABLE 3 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

TABLE 4 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)2 12 40 4

FIG. 3 illustrates an example of a frame structure in a NR system. FIG.3 is merely for convenience of explanation and does not limit the scopeof the present disclosure.

In Table 4, in case of μ=2, i.e., as an example in which a subcarrierspacing (SCS) is 60 kHz, one subframe (or frame) may include four slotswith reference to Table 3, and one subframe={1, 2, 4} slots shown inFIG. 3 , for example, the number of slot(s) that may be included in onesubframe may be defined as in Table 3.

Further, a mini-slot may consist of 2, 4, or 7 symbols, or may consistof more symbols or less symbols.

In regard to physical resources in the NR system, an antenna port, aresource grid, a resource element, a resource block, a carrier part,etc. May be considered.

Hereinafter, the above physical resources that may be considered in theNR system are described in more detail.

First, in regard to an antenna port, the antenna port is defined so thata channel over which a symbol on an antenna port is conveyed may beinferred from a channel over which another symbol on the same antennaport is conveyed. When large-scale properties of a channel over which asymbol on one antenna port is conveyed may be inferred from a channelover which a symbol on another antenna port is conveyed, the two antennaports may be regarded as being in a quasi co-located or quasico-location (QC/QCL) relation. Here, the large-scale properties mayinclude at least one of delay spread, Doppler spread, frequency shift,average received power, and received timing.

FIG. 4 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed in the presentdisclosure is applicable.

Referring to FIG. 4 , a resource grid consists of N_(RB) ^(μ)N_(sc)^(RB) subcarriers on a frequency domain, each subframe consisting of14·2μ OFDM symbols, but the present disclosure is not limited thereto.

In the NR system, a transmitted signal is described by one or moreresource grids, consisting of N_(RB) ^(μ)N_(sc) ^(RB) subcarriers, and2^(μ)N_(symb) ^((μ)) OFDM symbols, where N_(RB) ^(μ)≤N_(RB) ^(max,μ).N_(RB) ^(max,μ) denotes a maximum transmission bandwidth and may changenot only between numerologies but also between uplink and downlink.

In this case, as illustrated in FIG. 5 , one resource grid may beconfigured per numerology μ and antenna port p.

FIG. 5 illustrates examples of a resource grid per antenna port andnumerology to which a method proposed in the present disclosure isapplicable.

Each element of the resource grid for the numerology μ and the antennaport p is called a resource element and is uniquely identified by anindex pair (k,l), where k=0, . . . , N_(RB) ^(μ)N_(sc) ^(RB)−1 is anindex on a frequency domain, and l=0, . . . , 2^(μ)N_(symb) ^((μ))−1refers to a location of a symbol in a subframe. The index pair (k,l) isused to refer to a resource element in a slot, where l=0, . . . ,N_(symb) ^(μ)−1.

The resource element (k,l) for the numerology μ and the antenna port pcorresponds to a complex value a_(k,l) ^((p,μ)). When there is no riskfor confusion or when a specific antenna port or numerology is notspecified, the indices p and μ may be dropped, and as a result, thecomplex value may be a_(k,l) ^((p)) or a_(k,l) .

Further, a physical resource block is defined as N_(sc) ^(RB)=12consecutive subcarriers in the frequency domain.

Point A serves as a common reference point of a resource block grid andmay be obtained as follows.

-   -   offsetToPointA for PCell downlink represents a frequency offset        between the point A and a lowest subcarrier of a lowest resource        block that overlaps a SS/PBCH block used by the UE for initial        cell selection, and is expressed in units of resource blocks        assuming 15 kHz subcarrier spacing for FR1 and 60 kHz subcarrier        spacing for FR2;    -   absoluteFrequencyPointA represents frequency-location of the        point A expressed as in absolute radio-frequency channel number        (ARFCN);

The common resource blocks are numbered from 0 and upwards in thefrequency domain for subcarrier spacing configuration μ.

The center of subcarrier 0 of common resource block 0 for the subcarrierspacing configuration μ coincides with “point A”. A common resourceblock number n_(CRB) ^(μ) in the frequency domain and resource elements(k, l) for the subcarrier spacing configuration μ may be given by thefollowing Equation 1.

$\begin{matrix}{n_{CRB}^{\mu} = \lfloor \frac{k}{N_{sc}^{RB}} \rfloor} & \lbrack {{Equation}\mspace{14mu} 1} \rbrack\end{matrix}$

Here, k may be defined relative to the point A so that k=0 correspondsto a subcarrier centered around the point A. Physical resource blocksare defined within a bandwidth part (BWP) and are numbered from 0 toN_(BWP,i) ^(size)−1, where i is No. Of the BWP. A relation between thephysical resource block n_(PRB) in BWP i and the common resource blockn_(CRB) may be given by the following Equation 2.n _(CRB) =n _(PRB) +N _(BWP,i) ^(start)  [Equation 2]

Here, N_(BWP,i) ^(start) may be the common resource block where the BWPstarts relative to the common resource block 0.

Bandwidth Part (BWP)

The NR system may support up to 400 MHz per component carrier (CC). If aUE which operates in wideband CC operates while continuously turning onRF for all CCs, UE battery consumption may increase. Alternatively, whenseveral use cases (e.g., eMBB, URLLC, mMTC, V2X, etc.) which operate inone wideband CC are considered, different numerologies (e.g.,sub-carrier spacing) may be supported for each frequency band in thecorresponding CC. Alternatively, a capability for the maximum bandwidthmay vary for each UE. By considering this, the BS may instruct the UE tooperate only in a partial bandwidth rather than the entire bandwidth ofthe wideband CC and intends to define the corresponding partialbandwidth as the bandwidth part (BWP) for convenience. The BWP mayconsist of consecutive resource blocks (RBs) on the frequency axis andmay correspond to one numerology (e.g., sub-carrier spacing, CP length,slot/mini-slot duration).

A base station may configure multiple BWPs even within one CC configuredto the UE. As one example, a BWP occupying a relatively small frequencydomain may be configured in a PDCCH monitoring slot, and a PDSCHindicated in PDCCH may be scheduled onto a BWP larger than this.Alternatively, when UEs are concentrated on a specific BWP, some UEs maybe configured with other BWPs for load balancing. Alternatively,considering frequency domain inter-cell interference cancellationbetween neighboring cells, a partial spectrum of the entire bandwidthmay be excluded and both BWPs may be configured even in the same slot.That is, the base station may configure at least one DL/UL BWP to the UEassociated with the wideband CC and may activate at least one DL/UL BWP(by L1 signaling or MAC CE or RRC signaling) among configured DL/ULBWP(s) at a specific time, and switching may be indicated to anotherconfigured DL/UL BWP (by L1 signaling or MAC CE or RRC signaling) or atimer value may be switched to the fixed DL/UL BWP when a timer value isexpired based on a timer. In this case, the activated DL/UL BWP isdefined as an active DL/UL BWP. However, in a situation in which the UEis in an initial access process or before RRC connection is set up, theUE may not receive a configuration for the DL/UL BWP and in such asituation, the DL/UL BWP assumed by the UE is defined as an initialactive DL/UL BWP.

For example, if a specific field (e.g., BWP indicator field) indicatingthe BWP is included in DCI (e.g., DCI format 1_1) for scheduling of thePDSCH, a value of the corresponding field may be configured to indicatea specific DL BWP (e.g., active DL BWP) among a DL BWP set(pre-)configured for DL reception to the UE. In this case, the UEreceiving the DCI may be configured to receive DL data in the specificDL BWP indicated by the corresponding field. And/or, if a specific field(e.g., BWP indicator field) indicating the BWP is included in DCI (e.g.,DCI format 11) for scheduling of the PUSCH, a value of the correspondingfield may be configured to indicate a specific UL BWP (e.g., active ULBWP) among a UL BWP set (pre-)configured for UL transmission to the UE.In this case, the UE receiving the DCI may be configure to transmit ULdata in the specific UL BWP indicated by the corresponding field.

Physical Channel and General Signal Transmission

FIG. 6 illustrates physical channels and general signal transmission inused in 3GPP system. In a wireless communication system, the UE receivesinformation from the eNB through Downlink (DL) and the UE transmitsinformation from the eNB through Uplink (UL). The information which theeNB and the UE transmit and receive includes data and various controlinformation and there are various physical channels according to atype/use of the information which the eNB and the UE transmit andreceive.

When the UE is powered on or newly enters a cell, the UE performs aninitial cell search operation such as synchronizing with the eNB (S601).To this end, the UE may receive a Primary Synchronization Signal (PSS)and a (Secondary Synchronization Signal (SSS) from the eNB andsynchronize with the eNB and acquire information such as a cell ID orthe like. Thereafter, the UE may receive a Physical Broadcast Channel(PBCH) from the eNB and acquire in-cell broadcast information.Meanwhile, the UE receives a Downlink Reference Signal (DL RS) in aninitial cell search step to check a downlink channel status.

A UE that completes the initial cell search receives a Physical DownlinkControl Channel (PDCCH) and a Physical Downlink Control Channel (PDSCH)according to information loaded on the PDCCH to acquire more specificsystem information (S602).

Meanwhile, when there is no radio resource first accessing the eNB orfor signal transmission, the UE may perform a random access procedure(RACH) to the eNB (S603 to S606). To this end, the UE may transmit aspecific sequence to a preamble through a physical random access channel(PRACH) (S603 and S605) and receive a response message (Random AccessResponse (RAR) message) for the preamble through the PDCCH and acorresponding PDSCH. In the case of a contention based RACH, aContention Resolution Procedure may be additionally performed (S606).

The UE that performs the above procedure may then perform PDCCH/PDSCHreception (S607) and Physical Uplink Shared Channel (PUSCH)/PhysicalUplink Control Channel (PUCCH) transmission (S608) as a generaluplink/downlink signal transmission procedure. In particular, the UE mayreceive Downlink Control Information (DCI) through the PDCCH. Here, theDCI may include control information such as resource allocationinformation for the UE and formats may be differently applied accordingto a use purpose.

For example, in an NR system, DCI format 0_0 and DCI format 0_1 are usedfor scheduling of PUSCH in one cell, and DCI format 1_0 and DCI format1_1 are used for scheduling PDSCH in one cell. Information included inDCI format 0_0 is CRC scrambled by C-RNTI or CS-RNTI or MCS-C-RNTI andtransmitted. And, DCI format 0_1 is used for reserving PUSCH in onecell. Information included in DCI format 0_1 may be CRC scrambled byC-RNTI or CS-RNTI or SP-CSI-RNTI or MCS-C-RNTI and transmitted. DCIformat 1_0 is used for scheduling PDSCH in one DL cell. Informationincluded in DCI format 1_0 is CRC scrambled by C-RNTI or CS-RNTI orMCS-C-RNTI and transmitted. DCI format 1_1 is used for scheduling PDSCHin one cell. Information included in DCI format 1_1 is CRC scrambled byC-RNTI or CS-RNTI or MCS-C-RNTI and transmitted. DCI format 2_1 is usedto inform PRB(s) and OFDM symbol(s) that the UE may assume thattransmission is not intended. The following information included in DCIformat 2_1 such as preemption indication 1, preemption indication 2, . .. , preemption indication N is CRC scrambled by INT-RNTI andtransmitted.

Meanwhile, the control information which the UE transmits to the eNBthrough the uplink or the UE receives from the eNB may include adownlink/uplink ACK/NACK signal, a Channel Quality Indicator (CQI), aPrecoding Matrix Index (PMI), a Rank Indicator (RI), and the like. TheUE may transmit the control information such as the CQI/PMI/RI, etc.,via the PUSCH and/or PUCCH.

DL and UL Transmission/Reception Operation

Downlink Transmission/Reception Operation

FIG. 7 illustrates an example of a downlink transmission and receptionoperation.

Referring to FIG. 7 , the eNB may schedule downlink transmission such asthe frequency/time resource, the transport layer, a downlink precoder,the MCS, etc., (S701). Specifically, the eNB may determine a beam forPDSCH transmission to the UE. In addition, the UE may receive DownlinkControl Information (DCI) for downlink scheduling (i.e., includingscheduling information of the PDSCH) on the PDCCH (S702). DCI format 1_0or DCI format 11 may be used for the downlink scheduling andspecifically, DCI format 11 may include information such as thefollowing examples: Identifier for DCI formats, Bandwidth partindicator, Frequency domain resource assignment, Time domain resourceassignment, PRB bundling size indicator, Rate matching indicator, ZPCSI-RS trigger, Antenna port(s), Transmission configuration indication(TCI), SRS request, and Demodulation Reference Signal (DMRS) sequenceinitialization.

In particular, according to each state/index indicated in an antennaport(s) field, the number of DMRS ports may be scheduled, andsingle-user (SU)/multi-user (MU) transmission scheduling is alsoavailable. Specifically, the order of DMRS ports corresponding to thenumber of CWs may be predefined depending on dmrs-type and maxLength,and the number and/or order of DMRS ports may be indicated via anantenna port field of DCI. Further, it may be determined whether thedetermined DMRS ports are included in the same CDM group or differentCDM groups based on DMRS related parameters defined for each DM-RSconfiguration type.

For example, for DMRS configuration type 1, antenna port p {1000, 1001,1004, 1005} may be included in CDM group 0, and antenna port p {1002,1003, 1006, 1007} may be included in CDM group 1. For DMRS configurationtype 2, antenna port p {1000, 1001, 1006, 1007} may be included in CDMgroup 0, antenna port p {1002, 1003, 1008, 1009} may be included in CDMgroup 1, and antenna port p {1004, 1005, 1010, 1011} may be included inCDM group 2.

For example, for dmrs-Type=2, maxLength=1, and 1 CW, if ‘2’ is indicatedthrough an antenna port field of DMRS, it can be seen that the DMRS portis indicated as 0, 1 (i.e., 1000, 1001), and the DMRS ports areindicated within the same CDM group. For example, if ‘9’ is indicatedthrough the antenna port field of DMRS, it can be seen that the DMRSport is indicated as 0, 1, 2 (i.e., 1000, 1001, 1002), and DMRS portswithin different CDM groups are indicated.

In addition, the TCI field consists of 3 bits, and the QCL for the DMRSmay be dynamically indicated by indicating a maximum of 8 TCI statesaccording to the TCI field value. The UE may receive downlink data fromthe base station on the PDSCH (S703). When the UE detects a PDCCHincluding DCI format 1_0 or 1_1, the UE may decode the PDSCH accordingto an indication by the corresponding DCI.

Here, when the UE receives a PDSCH scheduled by DCI format 11, a DMRSconfiguration type may be configured by higher layer parameter“dmrs-Type” in the UE and the DMRS configuration type is used forreceiving the PDSCH. Further, in the UE, the maximum number offront-loaded DMRS symbols for the PDSCH may be configured by higherlayer parameter “maxLength.”

In the case of DMRS configuration type 1, when a single codeword isscheduled and an antenna port mapped to an index of {2, 9, 10, 11, or30} is designated in the UE or when two codewords are scheduled in theUE, the UE assumes that all remaining orthogonal antenna ports are notassociated with PDSCH transmission to another UE. Alternatively, in thecase of DMRS configuration type 2, when a single codeword is scheduledand an antenna port mapped to an index of {2, 10, or 23} is designatedin the UE or when two codewords are scheduled in the UE, the UE assumesthat all remaining orthogonal antenna ports are not related to PDSCHtransmission to another UE.

Two types including type 0 and type 1 are supported for resourceallocation of the frequency domain for PDSCH.

In the Type 0, resource block assignment information may include abitmap indicating a resource block group (RBG) assigned to the UE. Here,the RBG may be a set of consecutive virtual resource blocks, and may bedefined by higher layer parameter rbg-Size configured by PDSCH-Configand the size of the BWP. The RBGs may be indexed in increasing order offrequencies starting from a lowest frequency of the BWP. The RBGcorresponding to value of 1 in the bitmap is allocated to the UE, andthe RBG corresponding to value of 0 in the bitmap is not allocated tothe UE.

In the Type 1, resource block assignment information indicates, to ascheduled UE, a set of contiguously assigned non-interleaved orinterleaved virtual resource blocks within an active BWP (except thecase of decoding DCI format 1_0 in CSS using the size of CORESET 0 orusing the size of initial DL BWP). A downlink type 1 resource assignmentfield may consist of a resource indication value RIV corresponding to astarting virtual resource block RB_start and a length of contiguouslyassigned resource blocks L_RBs.

Physical resource blocks (PRBs) may be bundled, and precodinggranularity P′ when the UE receives the PDSCH may be assumed as aconsecutive resource block in the frequency domain. Here, P′ maycorrespond to one value of {2, 4, and wideband}. When P′ is determinedas wideband, the UE does not predict that the PDSCH is scheduled tonon-contiguous PRBs and the UE may assume that the same precoding isapplied to the allocated resource. On the contrary, when P′ isdetermined as any one of {2 and 4}, a Precoding Resource Block (PRG) issplit into P′ consecutive PRBs. The number of actually consecutive PRBsin each PRG may be one or more. The UE may assume that the sameprecoding is applied to consecutive downlink PRBs in the PRG.

In order to determine a modulation order in the PDSCH, a target coderate, and a transport block size, the UE may first read a 5-bit MCDfield in the DCI and determine the modulation order and the target coderate. In addition, the UE may read a redundancy version field in the DCIand determine a redundancy version. In addition, the UE may determinethe transport block size by using the number of layers before ratematching and the total number of allocated PRBs.

A transport block may be made up of one or more code block groups (CBG),and one CBG may be made up of one or more code blocks (CB). Also, in anNR system, data transmission and reception may be performed for eachCB/CBG as well as for each transport block. Accordingly, ACK/NACKtransmission and retransmission per CB/CBG also may be possible. The UEmay receive information on CB/CBG from the base station through a DCI(e.g., DCI format 0_1 and DCI format 1_1). Also, the UE may receiveinformation on a data transmission unit (e.g., TB/CB/CBG) from the basestation.

UL Transmission/Reception Operation

FIG. 8 illustrates an example of an uplink transmission and receptionoperation.

Referring to the FIG. 8 , the eNB may schedule uplink transmission suchas the frequency/time resource, the transport layer, an uplink precoder,the MCS, etc., (S801). In particular, the eNB may determine a beam forPUSCH transmission of the UE through the beam management operationsdescribed above. And, the UE may receive, from the eNB, DCI for uplinkscheduling (i.e., including scheduling information of the PUSCH) on thePDCCH (S802).

DCI format 0_0 or 0_1 may be used for the uplink scheduling and inparticular, DCI format 0_1 may include information such as the followingexamples: Identifier for DCI formats, UL/Supplementary uplink (SUL)indicator, Bandwidth part indicator, Frequency domain resourceassignment, Time domain resource assignment, Frequency hopping flag,Modulation and coding scheme (MCS), SRS resource indicator (SRI),Precoding information and number of layers, Antenna port(s), SRSrequest, DMRS sequence initialization, and Uplink Shared Channel(UL-SCH) indicator.

In particular, configured SRS resources in an SRS resource setassociated with higher layer parameter “usage” may be indicated by anSRS resource indicator field. Further, “spatialRelationInfo” may beconfigured for each SRS resource and a value of “spatialRelationInfo”may be one of {CRI, SSB, and SRI}.

In addition, the UE may transmit the uplink data to the eNB on the PUSCH(S803). When the UE detects a PDCCH including DCI format 0_0 or 0_1, theUE may transmit the corresponding PUSCH according to the indication bythe corresponding DCI. two schemes (Codebook based transmission schemeand non-codebook based transmission scheme) are supported for PUSCHtransmission.

In the case of the codebook based transmission, when higher layerparameter txConfig” is set to “codebook”, the UE is configured to thecodebook based transmission. On the contrary, when higher layerparameter txConfig” is set to “nonCodebook”, the UE is configured to thenon-codebook based transmission. When higher layer parameter “txConfig”is not configured, the UE does not predict that the PUSCH is scheduledby DCI format 0_1. When the PUSCH is scheduled by DCI format 00, thePUSCH transmission is based on a single antenna port. In the case of thecodebook based transmission, the PUSCH may be scheduled by DCI format0_0, DCI format 0_1, or semi-statically. When the PUSCH is scheduled byDCI format 0_1, the UE determines a PUSCH transmission precoder based onthe SRI, the Transmit Precoding Matrix Indicator (TPMI), and thetransmission rank from the DCI as given by the SRS resource indicatorand the Precoding information and number of layers field. The TPMI isused for indicating a precoder to be applied over the antenna port andwhen multiple SRS resources are configured, the TPMI corresponds to theSRS resource selected by the SRI. Alternatively, when the single SRSresource is configured, the TPMI is used for indicating the precoder tobe applied over the antenna port and corresponds to the correspondingsingle SRS resource. A transmission precoder is selected from an uplinkcodebook having the same antenna port number as higher layer parameter“nrofSRS-Ports”. When the UE is set to higher layer parameter “txConfig”set to “codebook”, at least one SRS resource is configured in the UE. AnSRI indicated in slot n is associated with most recent transmission ofthe SRS resource identified by the SRI and here, the SRS resourceprecedes PDCCH (i.e., slot n) carrying the SRI.

In the case of the non-codebook based transmission, the PUSCH may bescheduled by DCI format 0_0, DCI format 0_1, or semi-statically. Whenmultiple SRS resources are configured, the UE may determine the PUSCHprecoder and the transmission rank based on a wideband SRI and here, theSRI is given by the SRS resource indicator in the DCI or given by higherlayer parameter “srs-Resourcelndicator”. The UE may use one or multipleSRS resources for SRS transmission and here, the number of SRS resourcesmay be configured for simultaneous transmission in the same RB based onthe UE capability. Only one SRS port is configured for each SRSresource. Only one SRS resource may be configured to higher layerparameter “usage” set to “nonCodebook”. The maximum number of SRSresources which may be configured for non-codebook based uplinktransmission is 4. The SRI indicated in slot n is associated with mostrecent transmission of the SRS resource identified by the SRI and here,the SRS transmission precedes PDCCH (i.e., slot n) carrying the SRI.

Demodulation Reference Signal (DMRS)

A DMRS-related operation for PDSCH reception will be described.

When receiving PDSCH scheduled by DCI format 1_0 or receiving PDSCHbefore dedicated higher layer configuration of any of the parametersdmrs-AdditionalPosition, maxLength, and dmrs-Type, the UE assumes thatthe PDSCH is not present in any symbol carrying DM-RS except for PDSCHwith allocation duration of 2 symbols with PDSCH mapping type B, and asingle symbol front-loaded DM-RS of configuration type 1 on DM-RS port1000 is transmitted, and that all the remaining orthogonal antenna portsare not associated with transmission of PDSCH to another UE.

In addition, for PDSCH with mapping type A, the UE assumes thatdmrs-AdditionalPosition=‘pos2’ and up to two additional single-symbolDM-RS are present in a slot according to the PDSCH duration indicated inthe DCI. For PDSCH with allocation duration of 7 symbols for normal CPor 6 symbols for extended CP with mapping type B, the UE assumes thatone additional single-symbol DM-RS is present in the 5th or 6th symbolwhen the front-loaded DM-RS symbol is in the 1st or 2nd symbolrespectively of the PDSCH allocation duration. Otherwise, the UE assumesthat the additional DM-RS symbol is not present. And, for PDSCH withallocation duration of 4 symbols with mapping type B, the UE assumesthat no additional DM-RS are present. For PDSCH with allocation durationof 2 symbols with mapping type B, the UE assumes that no additionalDM-RS are present, and the UE assumes that the PDSCH is present in thesymbol carrying DM-RS.

FIG. 9 is a flow chart illustrating an example of a DL DMRS procedure.

A base station transmits DMRS configuration information to a UE, inS910.

The DMRS configuration information may refer to DMRS-DownlinkConfig IE.The DMRS-DownlinkConfig IE may include parameter dmrs-Type, parameterdmrs-AdditionalPosition, parameter maxLength, parameter phaseTrackingRS,etc.

The parameter dmrs-Type is a parameter for selection of a DMRSconfiguration type to be used for DL. In NR, the DMRS may be classifiedinto two configuration types: (1) DMRS configuration type 1 and (2) DMRSconfiguration type 2. The DMRS configuration type 1 is a type having ahigher RS density in the frequency domain, and the DMRS configurationtype 2 is a type having more DMRS antenna ports.

The parameter dmrs-AdditionalPosition is a parameter indicating theposition of an additional DMRS in the DL. If the corresponding parameteris not present, the UE applies value of pos2. In the DMRS, a firstposition of a front-loaded DMRS may be determined according to the PDSCHmapping type (type A or type B), and an additional DMRS may beconfigured to support a high speed UE. The front-loaded DMRS occupies 1or 2 consecutive OFDM symbols and is indicated by RRC signaling anddownlink control information (DCI).

The parameter maxLength is a parameter indicating the maximum number ofOFDM symbols for DL front-loaded DMRS. The parameter phaseTrackingRS isa parameter for configuring DL PTRS. If the corresponding parameter isnot present or has been canceled, the UE assumes that there is no DLPTRS.

The base station generates a sequence used for DMRS, in S920.

The sequence for DMRS is generated according to Equation 3 below.

$\begin{matrix}{{r(n)} = {{\frac{1}{\sqrt{2}}( {1 - {2 \cdot {c( {2n} )}}} )} + {j\frac{1}{\sqrt{2}}( {1 - {2 \cdot {c( {{2n} + 1} )}}} )}}} & \lbrack {{Equation}\mspace{14mu} 3} \rbrack\end{matrix}$

The pseudo-random sequence c(i) is defined by 3GPP TS 38.211 5.2.1. Thatis, c(i) may be a length-31 gold sequence using two m-sequences. Apseudo-random sequence generator is initialized by Equation 4 below.c _(init)=(2¹⁷(N _(symb) ^(slot) n _(s,f) ^(μ) +l+1)(2N _(ID) ^(s)^(SCID) +1)+2N _(ID) ^(s) ^(SCID) +n _(SCID))mod 2³¹  

Equation 4

where l is the OFDM symbol number within the slot, and n_(s,f) ^(μ) isthe slot number within a frame.

N_(ID) ⁰, N_(ID) ¹∈{0, 1, . . . , 65535} are given by the higher-layerparameter scramblingID0 and scramblingID1, respectively, in theDMRS-DownlinkConfig IE if provided and the PDSCH is scheduled by PDCCHusing DCI format 1_1 with the CRC scrambled by C-RNTI, MCS-C-RNTI, orCS-RNTI.

-   -   N_(ID) ⁰∈{0, 1, . . . , 65535} is given by the higher-layer        parameter scramblingID0 in the DMRS-DownlinkConfig IE if        provided and the PDSCH is scheduled by PDCCH using DCI format        1_0 with the CRC scrambled by C-RNTI, MCS-C-RNTI, or CS-RNTI.    -   N_(ID) ^(s) ^(SCID=N) _(ID) ^(cell), otherwise, the quantity        n_(SCID) ∈{0, 1} is given by the DMRS sequence initialization        field in the DCI associated with the PDSCH transmission if DCI        format 1_1 is used.

The base station maps the generated sequence to a resource element, inS930. Here, the resource element may mean including at least one oftime, frequency, antenna port, or code.

The base station transmits the DMRS to the UE on the resource element,in S940. The UE receives the PDSCH using the received DMRS.

Quasi-Co Location (QCL)

The antenna port is defined so that a channel over which a symbol on anantenna port is conveyed may be inferred from a channel over whichanother symbol on the same antenna port is conveyed. When properties ofa channel over which a symbol on one antenna port is conveyed may beinferred from a channel over which a symbol on another antenna port isconveyed, the two antenna ports may be considered as being in a quasico-located or quasi co-location (QC/QCL) relationship.

The channel properties include one or more of delay spread, Dopplerspread, frequency/Doppler shift, average received power, receivedtiming/average delay, and spatial RX parameter. The spatial Rx parametermeans a spatial (reception) channel property parameter such as an angleof arrival.

The UE may be configured with a list of up to M TCI-State configurationswithin the higher layer parameter PDSCH-Config to decode PDSCH accordingto a detected PDCCH with DCI intended for the corresponding UE and agiven serving cell, where M depends on UE capability.

Each TCI-State contains parameters for configuring a quasi co-locationrelationship between one or two DL reference signals and the DM-RS portsof the PDSCH.

The quasi co-location relationship is configured by the higher layerparameter qcl-Type1 for the first DL RS and qcl-Type2 for the second DLRS (if configured). For the case of two DL RSs, the QCL types are not bethe same, regardless of whether the references are to the same DL RS ordifferent DL RSs.

The quasi co-location types corresponding to each DL RS are given by thehigher layer parameter qcl-Type of QCL-Info and may take one of thefollowing values:

-   -   ‘QCL-TypeA’: {Doppler shift, Doppler spread, average delay,        delay spread}    -   ‘QCL-TypeB’: {Doppler shift, Doppler spread}    -   ‘QCL-TypeC’: {Doppler shift, average delay}    -   ‘QCL-TypeD’: {Spatial Rx parameter}

For example, if a target antenna port is a specific NZP CSI-RS, thecorresponding NZP CSI-RS antenna ports may be indicated/configured to beQCLed with a specific TRS in terms of QCL-TypeA and with a specific SSBin terms of QCL-TypeD. The UE receiving the indication/configuration mayreceive the corresponding NZP CSI-RS using the Doppler or delay valuemeasured in the QCL-TypeA TRS and apply the Rx beam used for QCL-TypeDSSB reception to the reception of the corresponding NZP CSI-RSreception.

The UE may receive an activation command by MAC CE signaling used to mapup to eight TCI states to the code point of the DCI field ‘TransmissionConfiguration Indication’.

In relation to the beam indication, the UE may be RRC-configured with alist for up to M candidate Transmission Configuration Indication (TCI)states for the purpose of at least Quasi Co-location (QCL) indication,where M may be 64.

Each TCI state may be configured in one RS set. IDs of each DL RS forthe purpose of spatial QCL (QCL Type D) at least in the RS set may referto one of DL RS types such as SSB, P-CSI RS, SP-CSI RS, and A-CSI RS.Initialization/update for the ID of DL RS(s) in the RS set that are usedat least for the purpose of spatial QCL may be performed at least byexplicit signaling.

The TCI-State IE associates one or two DL reference signals (RS) with acorresponding quasi co-location (QCL) type. The TCI-State IE may includeparameters such as bwp-Id/reference signal/QCL type.

A bwp-Id parameter indicates DL BWP where RS is positioned, a cellparameter indicates a carrier where RS is positioned, a reference signalparameter indicates a reference antenna port(s) that is a source ofquasi co-location for a corresponding target antenna port(s), or areference signal including it. The target antenna port(s) may be CSI-RS,PDCCH DMRS, or PDSCH DMRS. For example, a corresponding TCI state ID maybe indicated to NZP CSI-RS resource configuration information toindicate QCL reference RS information for NZP CSI-RS. As anotherexample, a TCI state ID may be indicated in each CORESET configurationto indicate QCL reference information for the PDCCH DMRS antennaport(s). As another example, a TCI state ID may be indicated through DCIto indicate QCL reference information for the PDSCH DMRS antennaport(s).

The descriptions (e.g., 3GPP system, frame structure, DL transmissionand reception operation, etc.) given above can be combined and appliedto methods described in the present disclosure to be described below, orcan be supplemented to clarify technical features of the methodsdescribed in the present disclosure. In the present disclosure, thepresence of a slash ‘/’ may mean that all and/or some of the contentsseparated by ‘/’ are included.

Multi-Transmission/Reception Point (TRP)-Related Operation

The coordinated multi point (CoMP) technique is a scheme in a pluralityof base stations exchange (e.g., use X2 interface) or utilize channelinformation (e.g., RI/CQI/PMI/LI, etc.) fed back from the user equipment(UE) to perform cooperative transmission with the UE, therebyeffectively controlling interference. According to the scheme used, thecooperative transmission may be divided into joint transmission (JT),coordinated scheduling (CS), coordinated beamforming (CB), dynamic pointselection (DPS), dynamic point blacking (DPB), and the like.

Non-coherent joint transmission (NCJT) may refer to cooperativetransmission that does not consider interference (that is, with nointerference). For example, the NCJT may be a scheme in which a basestation(s) transmits data to one UE through multiple TRPs by using thesame time resource and frequency resource. In this scheme, the multipleTRPs of the base station(s) may be configured to transmit data to UEthrough different layers by using different demodulation referencesignal (DMRS) ports. In other words, the NCJT may correspond to atransmission scheme in which transmission of a MIMO layer(s) from two ormore TRPs is performed without adaptive precoding between the TRPs.

The NCJT is divided into a fully overlapped NCJT in which the timefrequency resources transmitted by each TRP are fully overlapped, and apartially overlapped NCJT in which only sometime frequency resources areoverlapped. For example, in the case of partially overlapped NCJT, bothdata of a first base station (e.g., TRP 1) and data of a second basestation (e.g., TRP 2) may be transmitted in some of the time resourcesand/or frequency resources, and data of only one of the first and secondbase stations may be transmitted in the remaining time resources and/orfrequency resources.

TRP transmits data scheduling information to an NCJT receiving UE as DCI(Downlink Control Information). From the perspective of downlink controlinformation (DCI) transmission, M-TRP (multiple TRP) transmission may bedivided into i) M-DCI (multiple DCI) based M-TRP transmission in whicheach TRP transmits a different DCI and ii) S-DCI (single DCI) basedM-TRP transmission in which one TRP transmits DCI.

Firstly, the single DCI based MTRP scheme will be described. In thesingle DCI based MTRP scheme in which a representative TRP transmitsscheduling information for data transmitted by itself and datatransmitted by another TRP through one DCI, MTRPs cooperatively transmitone common PDSCH and each TRP participating in the cooperativetransmission spatially divides the corresponding PDSCH into differentlayers (i.e., different DMRS ports). In other words, MTRPs transmit onePDSCH but each TRP transmits only some of multiple layers of the PDSCH.For example, when 4-layer data is transmitted, TRP 1 transmits 2 layers,and TRP 2 transmits the remaining 2 layers to the UE.

In this case, scheduling information for the PDSCH is indicated to theUE through one DCI, and the corresponding DCI indicates which DMRS portuses information of which QCL RS and QCL type (which is different fromconventionally indicating the QCL RS and TYPE that are commonly appliedto all DMRS ports indicated by the DCI). That is, M TCI states (M=2 for2 TRP cooperative transmission) are indicated through the TCI field inthe DCI, and the QCL RS and type are identified by using M TCI stateswhich are different for M DMRS port groups. Also, DMRS port informationmay be indicated by using a new DMRS table.

As an example, in the case of the S-DCI, since all schedulinginformation for data transmitted by M TRPs should be delivered throughone DCI, the S-DCI may be used in an ideal backhaul (BH) environment inwhich two TRPs may be dynamically coordinated with each other.

Secondly, the multiple DCI based MTRP method will be described. MTRPstransmit different DCIs and PDSCHs, respectively (the UE receives N DCIsand N PDSCHs from N TRPs), and the corresponding PDSCHs are transmittedby (partially or wholly) overlapping on different time resources. Thecorresponding PDSCHs are transmitted through different scrambling IDs,and the corresponding DCIs may be transmitted through Coresets belongingto different Coreset groups (A coreset group may be identified as anindex defined in the coreset configuration of each Coreset. For example,if Coresets 1 and 2 are set to index=0 and Coresets 3 and 4 are set toindex=1, Coresets 1 and 2 belong to Coreset group 0 and Coresets 3 and 4belong to Coreset group 1. If no index is defined for a coreset, thismay be interpreted as index=0). If multiple scrambling IDs are set inone serving cell or two or more coreset groups are set, the UE may knowthat data is received by multiple DCI-based MTRP operation.

For example, the single DCI based MTRP scheme or the multiple DCI basedMTRP scheme may be indicated to the UE via separate signaling. As anexample, when a plurality of CRS patterns are indicated to the UE forMTRP operation for one serving cell, PDSCH rate matching for CRS may bedifferent depending on this MTRP operation is a single DCI based MTRPoperation or a multiple DCI based MTRP operation.

The base station described in this disclosure may be a generic term foran object that transmits/receives data to and from UE. For example, thebase station described herein may be a concept including one or moretransmission points (TPs), one or more transmission and reception points(TRPs), and the like. For example, multiple TPs and/or multiple TRPsdescribed herein may be included in one base station or included inmultiple base stations. In addition, the TP and/or TRP may include apanel of a base station, a transmission and reception unit, and thelike.

In addition, the TRP described in this disclosure means an antenna arrayhaving one or more antenna elements available in a network located at aspecific geographical location in a specific area. Although thisdisclosure is described with respect to “TRP” for convenience ofexplanation, the TRP may be replaced with a base station, a transmissionpoint (TP), a cell (e.g., a macro cell/small cell/pico cell, etc.), anantenna array, or a panel and understood and applied as such.

In addition, the CORESET group ID described in this disclosure may referto an index/identification information (e.g., ID)/indicator, etc. fordistinguishing a CORESET configured for/associated with each TRP/panel(or for each TRP/panel). In addition, the CORESET group may be agroup/union of CORESETs which is distinguished by theindex/identification information (e.g., ID) for distinguishing theCORESET and the CORESET group ID. For example, the CORESET group ID maybe specific index information defined in the CORESET configuration. Forexample, the CORESET group may be configured/indicated/defined by anindex defined in the CORESET configuration for each CORESET. The CORESETgroup ID may be configured/indicated via higher layer signaling (e.g.,RRC signaling)/L2 signaling (e.g., MAC-CE)/L1 signaling (e.g., DCI).

For example, ControlResourceSet information element (IE) that is ahigher layer parameter is used to configure a time/frequency controlresource set (CORESET). For example, the control resource set may berelated to detection and reception of downlink control information.Examples of the ControlResourceSet IE may include CORESET related ID(e.g., controlResourceSetID), an index of a CORESET pool for CORESET(e.g., CORESETPoolIndex), time/frequency resource configuration ofCORESET, and TCI information related to CORESET. For example, the indexof the CORESET pool (e.g., CORESETPoolIndex) may be set to 0 or 1. Theindex of the CORESET pool may mean a CORESET group ID. For example, theindex of the CORESET pool (e.g., CORESETPoolIndex) may correspond to theabove-described CORESET group ID.

M-TRP (Multiple-TRP) Transmission Scheme

M-TRP transmission by which multiple (e.g., M) TRPs transmit data to oneuser equipment (UE) may be divided into two main types of transmission:eMBB M-TRP transmission (or M-TRP eMMB) which is a scheme for increasinga transmission rate and URLLC M-TRP transmission (or M-TRP URLLC) whichis a scheme for increasing a reception success rate and reducinglatency.

URLLC M-TRP may mean that M-TRPs transmit the same TB (Transport Block)using different resources (e.g., layers/time resources/frequencyresources, etc.). A number of TCI state(s) may be indicated by DCI to aUE configured with the URLLC M-TRP transmission scheme, and datareceived using the QCL reference signal (RS) of each TCI state may beassumed to be the same TB. On the other hand, eMBB M-TRP may mean thatM-TRPs transmit different TBs using different resources (e.g.,layers/time resources/frequency resources, etc.). A number of TCIstate(s) may be indicated by DCI to a UE configured with the eMBB M-TRPtransmission scheme, and data received using the QCL RS of each TCIstate may be assumed to be different TBs. In relation to at least eMBBM-TRP, each TCI code point within DCI may correspond to 1 or 2 TCIstates. If 2 TCI states are activated within one TCI code point, eachTCI state for at least DMRS type 1 may correspond to one CDM group.

For example, the UE may decide/determine whether the corresponding M-TRPtransmission is URLLC transmission or eMBB transmission since it usesthe RNTI configured for MTRP-URLLC and the RNTI configured forMTRP-eMBB, separately. That is, if the CRC masking of the DCI receivedby the UE is performed using the RNTI configured for the MTRP-URLLCpurpose, this may correspond to URLLC transmission, and if the CRCmasking of the DCI is performed using the RNTI configured for theMTRP-eMBB purpose, this may correspond to eMBB transmission.

The URLLC M-TRP transmission scheme may include an SDM based scheme, aTDM based scheme, a FDM based scheme, etc to be described later. The UEmay also be configured with detailed schemes (e.g., SDM/FDM/TDM) of theURLLC M-TRP transmission scheme. For example, a higher layer parameter(e.g., repetitionScheme) for this may be defined, and one of the SDM,FDM or TDM schemes may be configured through the correspondingparameter. The UE may recognize that the same RB is transmitted usingother layer/time/frequency from M-TRP based on the configured scheme.

Method of Improving Reliability in Multi-TRPs

FIGS. 10A and 10B illustrates an example of a transmission/receptionmethod of improving reliability supported by a plurality of TRPs, andthe following two methods may be considered.

The example in FIG. 10A shows that a layer group transmitting the samecodeword (CW)/transport block (TB) correspond to different TRPs. Thatis, the same CW may be transmitted via different layers/layer groups. Inthis case, a layer group may refer to some kind of layer set made up ofone or more layers. As such, the amount of transmission resourcesincreases as the number of layers increases, and this is advantageous inthat robust channel coding with a low code rate can be used for TB. Inaddition, it is expected that the reliability of received signals may beimproved based on diversity gain due to different channels from aplurality of TRPs.

The example in FIG. 10B shows an example in which different CWs aretransmitted via layer groups corresponding to different TRPs. That is,different CWs may be transmitted through different layers/layer groups.In this case, it may be assumed that TBs corresponding to the first CW(CW #1) and the second CW (CW #2) are the same. Therefore, this can beseen as an example of repeated transmission of the same TB. In the caseof FIG. 10B, the code rate corresponding to the TB may be higher thanthat of (a) of FIG. 9 . Still, there is an advantage that a code ratecan be adjusted by indicating different redundancy version (RV) valuesfor encoding bits generated from the same TB according to a channelenvironment, or that a modulation order of each CW may be adjusted.

In FIG. 10A or FIG. 10B, the same TB is repeatedly transmitted viadifferent layer groups, and each layer group is transmitted by differentTRPs/panels, thereby increasing the data reception probability, whichmay be called spatial division multiplexing (SDM)-based URLLC M-TRPtransmission. A layer(s) belonging to different layer groups aretransmitted through DMRS ports belonging to different DMRS CDM groups,respectively.

In addition, although the above description regarding multiple TRPs hasbeen given with respect to a spatial division multiplexing (SDM) schemeusing different layers, it also may be extensively applied to afrequency division multiplexing (FDM) scheme based on differentfrequency domain resources (e.g., RB/PRB (set)), and/or a time divisionmultiplexing (TDM) scheme based on different time domain resources(e.g., slots, symbols, and sub-symbols).

For example, a TDM based URLLC M-TRP operation may include i) a schemein which one TRP transmits a TB in one slot (e.g., scheme 4) and ii) ascheme in which one TRP transmits a TB via several consecutive OFDMsymbols (i.e., a symbol group) (e.g., scheme 3). The scheme i) has aneffect of increasing the probability of data reception through the sameTB received from several TRPs in several slots. The scheme ii) has aneffect in which several TRPs can transmit the same TB via differentsymbol groups within one slot.

For example, if the above description is extended and applied to afrequency division multiplexing (FDM) scheme based on differentfrequency domain resources (e.g., RB/PRB (set)), the following operationmay be performed. This operation may be an operation of a case in whichthe FDM scheme is configured via a higher layer parameter (e.g.,repetitionScheme).

The different frequency domain resources may correspond to differentTRPs. Further, the different frequency domain resources may mean thatresource regions corresponding to the respective TRPs do not overlap ina frequency domain.

For example, the same CW/TB may be transmitted via the differentfrequency domain resources (e.g., RB/PRB (set)). Alternatively, forexample, a plurality of CWs (e.g., CW #1/CW #2) corresponding to thesame TB may be transmitted via the different frequency domain resources(e.g., RB/PRB (set)). This can be seen as an example of repeatedtransmission of the same TB. The UE configured with a plurality of TCIstates via DCI may receive data (e.g., CW/TB) using QCL RS of each TCIstate, and it may be assumed that the received data is the same TB.

FIGS. 11A and 11B illustrates an example of transmitting data to a UE(e.g., UE1) using different frequency resources at different TRPs (e.g.,TRP1 and TRP 2). More specifically, FIG. 11 illustrates an example of aFDM based URLLC M-TRP operation. Referring to FIG. 11A, TRP1 maytransmit data via a first frequency resource group (i.e., FRG #1), andTRP2 may transmit data via a second frequency resource group (i.e., FRG#2). Referring to FIG. 111B, the first frequency resource group and thesecond frequency resource group may overlap in the time domain and maynot overlap in the frequency domain. From a UE perspective, the UE mayreceive data from different TRPs in the first frequency resource groupand the second frequency resource group that do not overlap in thefrequency domain.

FIG. 11B illustrates a situation where the different frequency resourcegroups overlap in the time domain, by way of example. However, this ismerely an example for convenience of description and does not limit thetechnical scope of the present disclosure. Thus, a situation where thedifferent frequency resource groups partially overlap or do not overlapin the time domain may also be considered.

That is, multiple TRPs may transmit data in different frequency domainresources through the FDM scheme. In this instance, a frequency resourcegroup (FRG) may mean a set of frequency resources, and one frequencyresource group may include one or more frequency resources. For example,the FRG may be used by being replaced by a term such as PRG, PRG set,resource block group (RBG), and RBG set.

As above, in the case of transmitting a signal (or data) to the UE atdifferent TRPs, it can be expected that the reliability of the receivedsignal is improved based on a diversity gain because channels frommultiple TRPs are different.

In the above-described FDM based M-TRP operation, a single DCI basedM-TRP transmission in which a representative TRP of multiple TRPstransmits DCI may be performed.

As a method of allocating different frequency resources to differentTRPs using one DCI, the following two schemes may be considered.

FIGS. 12A and 12B illustrate an example of a method of allocatingfrequency resources to different TRPs via single DCI in a single DCIbased M-TRP operation (e.g., FRA method 1 and FRA method 2).

Referring to FIG. 12A, a frequency resource allocation (FRA) field inDCI indicates scheduling frequency resources for all TRPs, and differentTRPs may share the frequency resources scheduled by DCI based onsignaling (e.g., higher layer signaling/DCI) and/or rules. The FRA fieldin DCI may mean a ‘frequency domain resource assignment’ field of DCI.Hereinafter, such a method is referred to as ‘FRA method 1’ forconvenience of description.

Referring to FIG. 12B, the FRA field in DCI indicates schedulingfrequency resources for a specific TRP, and frequency resources mappedto other TRP may be allocated based on signaling (e.g., higher layersignaling/DCI) and/or rules. Hereinafter, such a method is referred toas ‘FRA method 2’ for convenience of description.

As a method of defining frequency resources which is basic for sizecalculation of a transport block (TB), (i) a method of considering allfrequency resources allocated to multiple TRPs (hereinafter, referred toas ‘reference frequency resource (FR) definition method 1’) and (ii) amethod of considering only frequency resources allocated to a specificTRP (hereinafter, referred to as ‘reference FR definition method 2’).

Compared with the above reference FR definition method 1, the referenceFR definition method 2 may be interpreted as a repeated transmissionform of a single TB. In this case, it may have an advantage that adifferent modulation order/RV, etc. can be applied to each TB.

Considering a combination of the method of allocating frequencyresources to different TRPs via single DCI (e.g., FRA method 1 and FRAmethod 2) and the reference FR determination method for the TB sizecalculation (e.g., reference FR definition method 1 and reference FRdefinition method 2), the part that may affect the current standard isdescribed below.

-   -   Combination of the FRA method 1 and the reference FR definition        method 1: signaling and/or rule for dividing frequency resources        allocated based on DCI into each TRP are required.

The TB size calculation may not be affected.

-   -   Combination of the FRA method 1 and the reference FR definition        method 2: signaling and/or rule for dividing frequency resources        allocated based on DCI into each TRP are required. Signaling        and/or rule for determining reference resources for TB size        calculation are also required. A separate MCS/RV indication may        be possible for each TB.    -   Combination of the FRA method 2 and the reference FR definition        method 1: signaling and/or rule for frequency resource        determination of other TRP based on frequency resources        allocated via DCI are required. Signaling and/or rule for        determining reference resources for TB size calculation are also        required.    -   Combination of the FRA method 2 and the reference FR definition        method 2: signaling and/or rule for frequency resource        determination of other TRP based on frequency resources        allocated via DCI are required. The TB size calculation may not        be affected. A separate MCS/RV indication may be possible for        each TB.

The present disclosure describes methods that can be proposed whenadditional UE/base station operation and/or signaling/rule are requireddepending on the combinations of the FRA method and the reference FRdefinition method when considering joint transmission (e.g., NCJT)between multiple base stations (e.g., multiple TPs/TRPs of one or morebase stations, etc.) and a UE in a wireless communication system, inparticular, for the FDM based M-TRP operation.

Specifically, proposal 1 proposes a method of configuring, via DCI, allfrequency resources for a plurality of TRPs jointly transmitting insingle DCI based M-TRP transmission and distributing and using theconfigured frequency resources into each TRP. Proposal 1-1 proposes amethod of assuming resource allocation based on the proposal 1 andreceiving PTRS from M-TRP. Proposal 2 proposes a method of configuring,via DCI, frequency resources for a specific TRP of a plurality of TRPsjointly transmitting in single DCI based M-TRP transmission anddetermining frequency resources of other TRP based on the configuredfrequency resources. The proposal 1 and the proposal 2 also propose areference resource determination method for TB size calculationaccording to each resource allocation method.

Methods described in the present disclosure are described based on oneor more TPs/TRPs of base station(s), but it is obvious that the methodscan be equally or similarly applied to transmission based on one or morepanels of the base station(s). The proposal 1, the proposal 1-1, and theproposal 2 described in the present disclosure assume a single DCI basedM-TRP operation and are described focusing on a situation where two TRPsoperate in the NCJT for convenience of description. However, it isobvious that the proposal 1, the proposal 1-2, and the proposal 2 can beapplied even if two or more TRPs operate.

[Proposal 1]

As in the above-described FRA method 1, current DCI provides only asingle field for frequency resource allocation (e.g., ‘Frequency domainresource assignment’ field), and frequency resources for all M-TRPsoperating in the NCJT through the corresponding field may beconfigured/indicated. A certain rule and/or signaling method between abase station and a UE shall be defined to determine a frequency resourcecorresponding to each TRP in the allocated frequency resources. Theproposal 1 of the present disclosure proposes a method of groupingresources for all the TRPs allocated via single DCI in units of specificresource (e.g., PRG/PRG set/RBG/RBG set, etc.), and determining afrequency resource for each TRP based on mapping between each group(/subgroup) and a TCI state associated with each TRP.

Specifically, if multiple TCI states are indicated to the UE (i.e., if aspecific code point associated with two or more TCI states is configuredvia DCI), frequency resources for respective TRPs may be distinguishedby corresponding TCI states related to different TRPs to frequencyresources. In other words, frequency resources corresponding torespective TCI states may be different in a frequency resource domainindicated via single DCI. A method of corresponding a TCI state relatedto a different TRP to a specific frequency resource in order to supportmulti-TRP transmission and an allocation method according to this aredescribed below.

Method 1) As an example of a method of allocating a different frequencyresource to a different TRP via single DCI, a PRG set consisting of oneor more precoding resource block groups (PRG) may be used. In thisinstance, one PRG set may include one or more PRGs, and the number ofPRGs constituting one PRG set may be configured to the UE via higherlayer signaling and/or DCI signaling. Alternatively, the number of PRGsmay be defied between the base station and the UE by a fixed rule.

If precoding granularity as 2 or 4 is configured/indicated to the UE, aprecoding resource block group (PRG) is divided into 2 or 4 consecutivePRBs. In other words, one PRG may consist of 2 or 4 consecutive PRBs.The UE may assume that the same precoding is applied to consecutivedownlink PRBs in the PRG.

If the precoding granularity as 2 or 4 is configured/indicated to theUE, a frequency resource corresponding to each TCI state may beallocated to the UE in units of certain PRG set consisting of multiplePRG(s). More characteristically, consecutive PRG sets may have featuresthat alternately correspond to different TCI states.

FIG. 13 illustrates an example of allocating a frequency resource toeach TRP based on a PRG set. FIG. 13 is merely an example forconvenience of description and does not limit the technical scope of thepresent disclosure. In FIG. 13 , CRB, PRG, and BWP mean a commonresource block, a precoding resource block group, a bandwidth part,respectively, and the same term may also be used in the followingdescription.

FIG. 13 illustrates that for each of Type 0 (e.g., RBG size 4) and Type1 that are a downlink resource allocation type of the above-describedfrequency domain, a PRG size is configured/indicated as 2 and a PRG setsize is configured as 1. If the PRG set size is 1, one PRG set may bedefined as a frequency resource related to one PRG configured/indicatedto the UE. TCI states related to different TRPs may be alternatelymapped to all the frequency resources scheduled for the UE based on DCIin units of PRG set. In other words, different TCI states may be mappedin units of PRG set, and the corresponding PRG set may be allocated tothe TRP associated with each TCI state. For example, a PRG set mapped toTCI state 1 may be a resource allocated to TRP 1, and a PRG set mappedto TCI state 2 may be a resource allocated to TRP 2.

For example, if the PRG set size is 2, one PRG set may consist of twoPRGs and may be alternately mapped to TCI states related to differentTRPs in units of PRG set.

The example of FIG. 13 may be seen as a method in which TCI statesrelated to different TRPs are alternately mapped in units of a certainPRG set based on a frequency resource scheduled for the UE. Morecharacteristically, a first TCI state of two TCI states indicated to theUE may correspond to an odd-numbered PRG set, and a second TCI state maycorrespond to an even-numbered PRG set (based on a low frequency indexin the frequency resources scheduled for the UE). Alternatively, thereverse order is also possible, and thus the first TCI state maycorrespond to the even-numbered PRG set and the second TCI state maycorrespond to the odd-numbered PRG set (based on the low frequency indexin the frequency resource scheduled for the UE). Alternatively, themapping order may be defined by a fixed rule, or may beconfigured/indicated via higher layer signaling and/or DCI signaling.

The above-described method has advantages in that a frequency diversitygain can be expected since frequency resources related to different TRPsare evenly spread in a scheduling band allocated to the UE via DCI, andthe size of the frequency resources allocated to different TRPs can beadjusted by adjusting the PRG set size.

Method 2) The example of FIG. 13 proposes a method of defining PRG setsbased on frequency resources scheduled for the UE and mapping differentTCI states to an odd-numbered PRG set and an even-numbered PRG set. Amethod of defining a PRG set based on a bandwidth part (BWP) on which aPDSCH is transmitted, and defining a mapping relationship with aspecific TCI state based on the PRG set is also possible.

FIG. 14 illustrates an example of defining a PRG set based on a BWP onwhich a PDSCH can be transmitted, and a mapping relationship between thePRG set and a TCI state in accordance with methods described in thepresent disclosure. FIG. 14 is merely an example for helpingunderstanding of the present disclosure and does not limit the technicalscope of the present disclosure.

FIG. 14 illustrates that for each of Type 0 (e.g., RBG size 4) and Type1 that are a downlink resource allocation type of the above-describedfrequency domain, a PRG size is configured/indicated as 4 and a PRG setsize is configured as 1. As can be seen from the case of the Type 0 ofFIG. 14 , since the PRG set is defined based on the BWP on which thePDSCH can be transmitted, the TCI state related to the same TRP may berelated to the consecutive PRG sets within the frequency resourceactually scheduled for the UE (unlike the above example of FIG. 13 ).For example, TCI state 1 may be equally mapped to a PRG sets subsequentto a PRG set mapped to the TCI state 1.

When compared to the method of FIG. 13 , if the method of FIG. 14 isapplied, there are advantages in that frequency resource domains can besemi-statically distinguished between different TRPs, and schedulingcomplexity in each TRP can be reduced and scheduling freedom can beincreased since scheduling between TRPs does not affect each other.

In the examples of the above-described method 1/method 2/FIG. 13 /FIG.14 , frequency resources related to different TRPs may overlap,partially overlap, or non-overlap in the time domain.

Method 3) If precoding granularity configured/indicated to the UE, thatis, a size of the PRG corresponds to wideband, the UE does not expect tobe scheduled with non-contiguous PRBs, and the UE may assume that thesame precoding is applied to the allocated resources. In this case, amethod of dividing equally or as evenly as possible a frequency resourcedomain allocated to the UE via DCI and mapping them to different TCIstates may be considered.

Specifically, if precoding granularity is configured/indicated to the UEas wideband, a frequency resource corresponding to each TCI state may beallocated to the UE as a certain RB set/RBG set consisting of multiplecontiguous resource blocks (RBs)/resource block groups (RBGs). In thisinstance, it may be characterized in that sizes of RB sets/RBG setsrelated to different TCI states are equal to each other or are as evenlyas possible.

A specific mode may be configured/indicated to the UE based on signaling(e.g., higher layer signaling/DCI signaling) and/or rules and/or RNTI sothat the UE operates according to the method. For example, if CRC checkis successful via a specific RNTI, DCI for frequency resource allocationmay be interpreted according to the proposed method.

FIG. 15 illustrates an example of a method of mapping a TCI stateassociated with each TRP according to a resource allocation method of afrequency domain for a PDSCH. More specifically, FIG. 15 illustrates anexample of a case where (a) 4 RBGs, (b) 3 RBGs, and (c) 3 RBGs areallocated to the UE for Type 0 (e.g., RBG size 4) and a case where (d)consecutive 16 RBs are allocated to the UE for Type 1. In the example ofFIG. 15 , frequency resources related to different TRPs may overlap,partially overlap, or non-overlap in the time domain. FIG. 15 is merelyan example for helping understanding of the present disclosure and doesnot limit the technical scope of the present disclosure.

In the example of FIG. 15 , if the UE is allocated (a) 4 RBGs in theType 0, the UE may map the same frequency resource to different TRPs inunits of RGB/RB. If the UE is allocated 3 RBGs (e.g., cases (b) and(c)), a size of a resource related to each TRP may vary depending onwhether to divide in units of RGB (b) or in units of RGB (c). In theType 1, frequency resources may be mapped to different TRPs in units ofRB (d).

In both the Type 0 and Type 1, sizes of resources mapped to differentTRPs may be different from each other depending on units of resourceallocation. In this case, a size of a resource related to a specific TRPmay be larger. To avoid this case, the base station can scheduleresources so that the UE assumes that sizes of resources related todifferent TRPs are the same.

As in the example of FIG. 15 , if a frequency resource domain allocatedto the UE via single DCI is divided equally or as evenly as possible andis mapped to different TCI states, there is advantages being able toallocate consecutive frequency resources of a widest domain for each ofthe two TRPs and improve a channel estimation performance for a channelrelated to each TRP by providing the maximum PRG size. In the existingoperation, the case where the precoding granularity isconfigured/indicated to the UE as wideband may be used for the purposeof helping a channel estimation method by notifying the UE thatconsecutive frequency resources to which the same precoding is appliedare allocated. Therefore, when utilizing it, the case may be used forthe purpose of indicating that consecutive frequency resources to whichthe same precoding is applied to each of the different TRPs areallocated as in the above proposed operation.

In addition, for example, for the method 3, a first TCI state of two TCIstates indicated to the UE may correspond to a first RB set/RBG set, anda second TCI state may correspond to a second RB set/RBG set (based on alow frequency index in the frequency resources scheduled for the UE).(The reverse order is also possible, and the mapping order may bedefined by a fixed rule, or may be configured/indicated via higher layersignaling and/or DCI signaling.)

As in the method 3, if different frequency resources, morecharacteristically, different RB sets/RBG sets are mapped to differentTCI states indicated to the UE, the PRG, i.e., the precoding granularitymay be defined by the corresponding RB set/RBG set from a UEperspective.

For example, when PRG=‘Wideband’ is configured and the number of TCIstates is greater than 1 (i.e., >1), the UE may assume that only anantenna port included in a band corresponding to the ‘scheduledBW/number of TCI states’ is the same antenna port. And/or, the UEassumes that PRG=‘scheduled BW/number of TCI states’. Alternatively,separate precoding granularity may be defined to support the aboveoperation. For example, separate precoding granularity ofPRG=‘sub_wideband’=‘scheduled BW/number of TCI states’ can be defined,and the UE to which the corresponding granularity isconfigured/indicated may perform the proposed operation.

In the above example, a reason that the resource domain corresponding toeach TCI state can be expressed as the RB set/RBG set is as follows.There are Type 0 and Type 1 as a method of allocating frequencyresources to the UE. In the Type 0, an RBG consisting of multiple RBs isdefined as a resource unit, and frequency resources may be allocatedbased on a bitmap scheme defined in units of RBG. In the Type 1,frequency resources consisting of consecutive RBs may be allocated inunits of RB. As such, since the minimum unit of frequency allocation mayvary depending on the frequency resource allocation method, as in theabove-described proposal method, the minimum unit of frequencyallocation for defining frequency resources related to different TCIstates may vary depending on the frequency allocation method.

A method of defining equally or as evenly as possible the size of the RBset/RBG set related to the different TCI states may be described below.

For a resource allocation method of a frequency domain of the Type 0,the total number of RBGs scheduled for the UE via DCI may be expressedas N_(RBG) ^(sched).

If mod(N_(RBG) ^(sched),2)=0, the number of RBGs of an RB set related toeach TCI state may be N_(RBG) ^(sched)/2 and a size of a frequencyresource related to each TCI state may be equally allocated.

If mod(N_(RBG) ^(sched),2) #0, the number of RBGs of an RB set relatedto TCI state #1 may be ┌N_(RBG) ^(sched)/2┐, and the number of RBGs ofan RB set related to TCI state #2 may be ┌N_(RBG) ^(sched)/2┐−1, where ┌┐ means a ceil operation, and the corresponding operation may bereplaced by floor/round, etc.

For a resource allocation method of a frequency domain of the Type 1,the number of consecutive RBs scheduled for the UE via DCI may beexpressed as L_(RBs).

If mod(L_(RBs), 2)=0, the number of RBGs of an RB set related to eachTCI state may be L_(RBs)/2, and a size of a frequency resource relatedto each TCI state may be equally allocated.

If mod(L_(RBs), 2)≠0, the number of RBGs of an RB set related to TCIstate #1 may be ┌L_(RBs)/2┐, and the number of RBGs of an RB set relatedto TCI state #2 may be ┌L_(RBs)/2┐−1.

In the above description, ┌ ┐ means a ceil operation, and thecorresponding operation may be replaced by floor/round, etc.

A method of defining a reference FR for TB calculation is describedbased on the methods (e.g., methods 1/2/3, etc.) of the above-describedproposal 1.

In the ‘reference FR definition method 1’ for the FRA method 1 describedin the proposal 1, i.e., when considering all the frequency resourcesallocated to multiple TRPs, since the frequency resource indicated viaDCI coincides with a sum of frequency resources used for PDSCHtransmission via different TRPs, a method of calculating the current TBsize may be used as it is.

On the other hand, in the ‘reference FR definition method 2’ for the FRAmethod 1 described in the proposal 1, i.e., when considering only thefrequency resource allocated to a specific TRP, a method is necessary todetermine the TB size calculation based on the frequency resource tomapped to which TCI state related to which TRP when the UE calculatesthe transport block (TB) size.

The UE can know how a TCI state related to each TRP is mapped tofrequency resource scheduled via single DCI according to the methods ofthe proposal 1 and/or the embodiments. Therefore, when the UE calculatesthe TB size, the UE can calculate the TB size based on a frequencyresource to which a TCI state related to a specific TRP is mapped basedon signaling (e.g., higher layer signaling/DCI) and/or rules between thebase station and the UE.

For example, a rule of defining a frequency resource mapped to aspecific TCI state as a reference resource for TB size calculation maybe defined between the base station and the UE. As an example, the UEmay define to calculate the TB size based on a frequency resource mappedto a first TCI state. According to the current standard, frequencyresources scheduled via DCI are applied to the TB size calculation, butif the above method is applied, only a part of the frequency resourcesscheduled via DCI may be applied to the TB size calculation.

The above example has described an example of calculating the TB sizebased on a frequency resource mapped to ‘a first TCI state’, but it maybe defined to calculate the TB size based on a frequency resource mappedto a second TCI state. That is, one of two TCI states (e.g., the firstTCI state and the second TCI state) may be selected by a fixed rule, andit may be defined to calculate the TB size based on a frequency resourcecorresponding to the selected TCI state.

As another example, a method for a base station to transmit, to a UE,information for a specific TRP (or specific TCI state) that is basic forthe TB size calculation may also be considered. For example, theinformation may be transmitted using the existing defined DCI field. Ifthe method of the proposal 1 is applied, a field for DMRS portindication (e.g., ‘Antenna port(s)’ field) can be reduced by optimizinga DMRS table. Thus, a part (e.g., MSB(s)/LSB(s)) of bits for definingthe existing field for DMRS port indication can be used for the aboveobject.

The field for DMRS port indication described in the above example ismerely an example and does not limit the technical scope of the presentdisclosure. Thus, another specific field within DCI may be used inaddition to the field for DMRS port indication. The existing fielddefined in the current standard may also be used, or a new field for theabove proposal may also be defined.

For example, the UE may select a reference frequency resource for the TBsize calculation based on the size of frequency resources (e.g., thenumber of PRBs, etc.) mapped to the same TCI state. As an example, theUE may select a frequency resource based on the number of PRBs mapped toeach TCI state to calculate the TB size. The UE may determine afrequency resource corresponding to a TCI state to which more or fewerPRBs are mapped (/allocated) as a reference resource for the TB sizecalculation, and may calculate the TB size based on the determinedreference resource.

As another example, an index of the frequency resource mapped to thesame TCI state may be a reference in order to select the frequencyresource for calculating the TB size. For example, the UE may calculatethe TB size based on a frequency resource corresponding to a TCI statemapped (/allocated) to a lowest or highest index.

As described above, in the ‘reference FR definition method 2’ for the‘FRA method 1’, i.e., if only a frequency resource (allocated to aspecific TRP) to which a specific TCI state is mapped is used for the TBsize calculation, (i) PDSCH (e.g., PDSCH 1) transmitted via a frequencyresource applied to the TB size calculation and (ii) PDSCH (e.g., PDSCH2) transmitted via other resource may be distinguished. The PDSCH (e.g.,PDSCH 2) transmitted via the other resource may be interpreted as arepeatedly transmitted PDSCH. In this instance, RV and/or modulationorder of the PDSCH 1 and the PDSCH 2 may be different from each other.To this end, part (e.g., MSB(s)/LSB(s)) of the existing bits used in thefield for DMRS port indication through the optimization of the DMRStable and/or a TB information field for indicating MCS/RV/NDI of asecond TB may be differently interpreted.

Further, in addition to the methods and/or embodiments according to the‘FRA method 1’ and the ‘reference FR definition method 2’, a rule forwhich modulation and coding scheme (MCS) value is used to calculate theTB size needs to be defined between the base station and the UE. Thebase station may indicate respective MCS values for TB 1/TB 2 to the UEvia a field in DCI. A method of determining a specific value to be usedfor TB size calculation among multiple MCS values indicated to the UEvia DCI may be necessary. A rule for determining a specific MCS value tobe used for TB size calculation may be defined between the UE and thebase station.

As an example, if a higher layer parameter,‘maxNrofCodeWordsScheduledByDCI’ value, meaning the maximum number ofCWs that can be scheduled by DCI is set to 1, the TB size may becalculated based on a MCS value indicated via a MCS field correspondingto TB 1.

As another example, if the ‘maxNrofCodeWordsScheduledByDCI’ value is setto 2, and the corresponding TB (e.g., TB1/TB2) is indicated as‘disabled’ as values of MCS and RV fields corresponding to TB 1 or TB 2are indicated as a specific value (i.e., MCS=26 and RV=1), the TB sizemay be calculated based on an MCS value indicated via the MCS fieldcorresponding to a TB (e.g., TB1/TB2) indicated as ‘enabled’.

As another example, if the ‘maxNrofCodeWordsScheduledByDCI’ value is setto 2 and both the two TBs (e.g., TB1 and TB2) are indicated as‘enabled’, an MCS value to be applied for the TB size calculation may bedetermined based on a TCI state corresponding to the frequency resourceselected above for calculating the TB size. For example, it may beassumed that a first TCI state corresponds to TB 1 and a second TCIstate corresponds to TB 2. If the selected frequency resource forcalculating the TB size corresponds to the first TCI state, the TB sizemay be calculated based on an MCS value indicated via an MCS fieldcorresponding to the TB 1. If the selected frequency resource forcalculating the TB size corresponds to the second TCI state, the TB sizemay be calculated based on an MCS value indicated via an MCS fieldcorresponding to the TB 2.

The above example has assumed that the first TCI state corresponds tothe TB 1 and the second TCI state corresponds to the TB 2, but it isobvious that the correspondence between the TCI state and the TB is notlimited to the above example. For example, the correspondence betweenthe TCI state and the TB may be defined by a specific relationship witha fixed rule between the base station and the UE, or may beconfigured/indicated to the UE via signaling of the base station.

As another example, if the ‘maxNrofCodeWordsScheduledByDCI’ value is setto 2 and both the two TBs (e.g., TB1 and TB2) are indicated as‘enabled’, an MCS value to be applied for the TB size calculation may bedetermined based on the MCS value indicated via the MCS fieldcorresponding to each TB. For example, the TB size may be calculatedbased on a lower or higher MCS value. Further, a frequency resource tobe applied for the TB size calculation may be determined depending onthe TB corresponding to the MCS field applied for the TB sizecalculation. For example, it may be assumed that a first TB 1corresponds to a first TCI state and a second TB 2 corresponds to asecond TCI state. If an MCS field selected for calculating the TB sizecorresponds to the TB 1, the TB size may be calculated based on afrequency resource corresponding to the first TCI state. If an MCS fieldselected for calculating the TB size corresponds to the TB 2, the TBsize may be calculated based on a frequency resource corresponding tothe second TCI state.

The above example has assumed that the TB 1 corresponds to the first TCIstate and the TB 2 corresponds to the second TCI state, but it isobvious that the correspondence between the TB and the TCI state is notlimited to the above example. For example, the correspondence betweenthe TB and the TCI state may be defined by a specific relationship witha fixed rule between the base station and the UE, or may beconfigured/indicated to the UE via signaling of the base station.

As another example, if the ‘maxNrofCodeWordsScheduledByDCI’ value is setto 2 and both the two TBs (e.g., TB1 and TB2) are indicated as‘enabled’, the TB size may be calculated based on an MCS value indicatedvia an MCS field corresponding to a specific TB. In this instance, thespecific TB may be defined by the fixed rule between the base stationand the UE, or may be configured/indicated to the UE via signaling ofthe base station. For example, the specific TB may be defined by thefixed rule so that the TB size is calculated based on an MCS valueindicated in an MCS field corresponding to TB 1.

The frequency resource allocated via one DCI in the single DCI basedM-TRP operation through the methods and/or embodiments of the proposal 1described above may be distributed for each TRP through the mappingbetween the TCI state and the frequency resource. The referencefrequency resource for the TB size calculation may also be determinedthrough the methods and/or embodiments of the proposal 1 describedabove.

[Proposal 1-1]

In Proposal 1-1, a method of transmitting a phase-tracking referencesignal (PTRS) at different TRPs is described based on the frequencyresource configuration method and the reference resource configurationmethod for TB calculation of the proposal 1 described above.

In the 5G NR standard, the PTRS has been introduced to compensate forimpairment generated by a phase noise in a high frequency band. This isbecause the phase noise causes a common phase error (CPE) and aninter-carrier interference (ICI) in a frequency domain.

Operations related to a DL PTRS and an UL PTRS are described in detailbelow. The detailed description related to the PTRS can be confirmed inclause 7.4.1.2 of TS38.211 and clause 5.1.6.3 of TS38.214.

FIG. 16 is a flow chart illustrating an example of a DL PTRS procedure.

Abase station transmits PTRS configuration information to a UE, inS1610. The PTRS configuration information may refer toPTRS-DownlinkConfig IE. The PTRS-DownlinkConfig IE may includefrequencyDensity parameter, timeDensity parameter, epre-Ratio parameter,resourceElementOffset parameter, etc.

The frequencyDensity parameter is a parameter representing a presenceand a frequency density of a DL PTRS as a function of scheduled BW. ThetimeDensity parameter is a parameter representing the presence and atime density of the DL PTRS as a function of modulation and codingscheme (MCS). The epre-Ratio parameter is a parameter representing anenergy per resource element (EPRE) between a PTRS and a PDSCH.

The frequencyDensity parameter and the timeDensity parameter indicatethresholds ptrs-MCSi (i=1, 2, 3, and 4), and N_RB,i (i=0 and 1) ofTables 6 and 7. The Table 6 represents the time density of the PTRS as afunction of scheduled MCS. The Table 7 represents the time density ofthe PTRS as a function of scheduled bandwidth.

TABLE 6 Scheduled MCS Time density (L_(PT-RS)) I_(MCS)< ptrs-MCS₁ PT-RSis not present ptrs-MCS1 ≤ I_(MCS) < ptrs-MCS2 4 ptrs-MCS2 ≤ I_(MCS) <ptrs-MCS3 2 ptrs-MCS3 ≤ I_(MCS) < ptrs-MCS4 1

TABLE 7 Scheduled bandwidth Frequency density (K_(PT-RS)) N_(RB) <N_(RB0) PT-RS is not present N_(RB0) ≤ N_(RB) < N_(RB1) 2 N_(RB1) ≤N_(RB) 4

A pattern of the PTRS may be determined depending on a density of afrequency domain and a density of a time domain. The density of thefrequency domain (i.e., the frequency density of the PTRS) may mean aspacing between the PTRSs (e.g., the number of RBs) in the frequencydomain. The density of the time domain (i.e., the time density of thePTRS) may mean a spacing between the PTRSs (e.g., the number of symbols)in the time domain.

Referring to Tables 6 and 7, the time density of the PTRS may varydepending on an MCS scheduled for the UE, and the frequency density ofthe PTRS may vary depending on a bandwidth scheduled for the UE. Thetime density/frequency density of the PTRS may vary based on thresholds(e.g., ptrs-MCS1/2/3/4) of the MCS and thresholds (e.g., N_RB0/1) of thebandwidth configured via the PTRS configuration information (e.g.,PTRS-DownlinkConfig).

The base station generates a sequence used for the PTRS, in S1620. Asshown in Equation 5 below, the sequence for the PTRS is generated usinga DMRS sequence of the same subcarrier. The sequence generation for thePTRS may be differently defined depending on whether transform precodinghas been enabled, and Equation 5 below represents an example where thetransform precoding is disabled.r _(k) =r(2m+k′)  

Equation 5

Here, r(2m+k′) is a DMRS given in a location l₀ and a subcarrier k.

That is, the sequence of the PTRS uses a sequence of the DMRS, and morespecifically, the sequence of the PTRS in the subcarrier k is the sameas a sequence of the DMRS in the subcarrier k.

The base station maps the generated sequence to a resource element, inS1630. Here, the resource element may mean including at least one oftime, frequency, antenna port or code.

A location of the PTRS in the time domain starts from a starting symbolof PDSCH allocation and is mapped at a specific symbol spacing. If aDMRS symbol is present, the mapping is performed from a symbol next tothe DMRS symbol. The specific symbol spacing may be 1, 2 or 4 symbols.

A frequency location of the PTRS in relation to resource element mappingof the PTRS is determined by a frequency location of an associated DMRSport and higher layer parameter UL-PTRS-RE-offset. Here,UL-PTRS-RE-offset is included in PTRS configuration and indicates asubcarrier offset for UL PTRS for CP-OFDM.

For DL, the PTRS port is related to a DMRS port of a lowest index amongscheduled DMRS ports. And, for UL, the base station configures whichDMRS port is related to the PTRS port via UL DCI.

The base station transmits the PTRS to the UE on a resource element, inS1640. The UE performs a compensation for a phase noise using thereceived PTRS.

An UL PTRS related operation is similar to the DL PTRS related operationmentioned above, and the names of the parameters related to the DL PTRSmay be replaced by the names of the parameters related to the UL PTRS.That is, PTRS-DownlinkConfig IE may be replaced by PTRS-UplinkConfig IE,and in the DL PTRS related operation, the base station may be replacedby the UE and the UE may be replaced by the base station. In the samemanner, the sequence generation for the PTRS may be differently defineddepending on whether transform precoding has been enabled.

According to the methods and/or embodiments of the proposal 1 describedabove, if precoding granularity is configured/indicated to the UE as 2or 4, a frequency resource corresponding to each TCI state is allocatedto the UE in units of PRG set consisting of multiple PRG(s), anddifferent TCI states alternately (intersecting) correspond toconsecutive PRG sets, there may be a problem that the PTRS cannot betransmitted in a frequency resource corresponding to a specific TCIstate. For example, if a spacing at which the PTRS is transmitted in thefrequency domain depending on the frequency density of the PTRS isgreater than one PRG set corresponding to the same TCI state, the PTRSmay not be mapped to PRG sets of specific order.

FIG. 17 illustrates an example of a mapping relationship betweenscheduled RBs and a TCI state corresponding to each TRP and an exampleof RBs on which PTRS is transmitted, when precoding granularity isconfigured as 2 in a frequency domain and a PRG set includes one PRG. InFIG. 17 , a spacing at which PTRS is transmitted is 4 RBs. FIG. 17 ismerely an example for convenience of description and does not limit thetechnical scope of the present disclosure.

Referring to FIG. 17 , PTRS is transmitted only in a frequency resourcecorresponding to a specific TRP (e.g., TRP #1). This is because a PTRSdensity of a frequency resource and a RB on which the PTRS istransmitted are defined to have to be determined based on the entirebandwidth scheduled to the UE via DCI according to the current standard.However, as in the above example, when the PTRS is transmitted only inthe frequency resource corresponding to the specific TRP, if phasesources of different TRPs corresponding to different TCI states aredifferent, large performance degradation may occur because an influenceof a phase noise for data transmitted from the specific TRP cannot becompensated.

Accordingly, the proposal 1-1 of the present disclosure proposes amethod (e.g., embodiments 1/2/3/4/5) of transmitting/receiving the PTRSin respective frequency resources corresponding to different TRPs, i.e.,corresponding to different TCI states in order to solve the aboveproblem. Hereinafter, methods to be described below may be independentlyperformed, or one method may be combined and applied to another method,or partial configuration of one method may be applied by being replacedby partial/all configuration of another method. Further, methods and/orembodiments (e.g., embodiments 1/2/3/4/5) of the proposal 1-1 may beapplied even if the precoding granularity is 2, 4 or wideband.

First, in FDM based M-TRP joint transmission, a method of determining afrequency density of the PTRS is described.

As described above, the frequency density of the PTRS may vary dependingon a bandwidth scheduled for the UE (e.g., the number of scheduled RBs).The frequency density of the PTRS may vary depending based on thresholds(e.g. N_RB0/1) of a bandwidth configured via PTRS configurationinformation (e.g., PTRS-DownlinkConfig). The frequency density of thePTRS may be determined based on the above-described Table 7. Thefrequency density of the PTRS may be determined through a comparison ofthresholds (e.g., N_RB0/1) configured via a scheduled bandwidth N_RB anda higher layer parameter. In the following description, a PTRS frequencydomain density may mean K_PT-RS of the above Table 7. A bandwidthconsidered to determine the PTRS frequency domain density may mean N_RB(e.g., the number of resource blocks) of the above Table 7.

Embodiment 1) To determine a frequency domain density of a PTRS (i.e., afrequency density of the PTRS), a PTRS frequency domain density may bedetermined based on only a bandwidth corresponding to a specific TCIstate among all bandwidths scheduled via DCI not all the bandwidthsscheduled via the DCI.

For example, the bandwidth corresponding to the specific TCI state amongall the bandwidths scheduled via the DCI may be a bandwidthcorresponding to a first TCI state or a second TCI state. The specificTCI state may be defined by a fixed rule between a base station and aUE, or may be configured/indicated to the UE via high layer signalingand/or DCI signaling.

For example, by comparing the bandwidth (i.e., N_RB) corresponding tothe specific TCI state with thresholds (e.g., N_RB0/1) configured by aparameter frequencyDensity, the frequency density (i.e., K_PT-RS) of thePTRS may be determined according to the above Table 7. The bandwidth(i.e., N_RB) corresponding to the specific TCI state may mean a resourceblocks (e.g., PRB) to which the specific TCI state is mapped.Specifically, if the bandwidth (i.e., N_RB) corresponding to thespecific TCI state is less than N_RB0, the PTRS may not exist. If thebandwidth (i.e., N_RB) corresponding to the specific TCI state isgreater than or equal to N_RB0 and is less than N_RB1, the frequencydensity of the PTRS may be 2. If the bandwidth (i.e., N_RB)corresponding to the specific TCI state is greater than or equal toN_RB1, the frequency density of the PTRS may be 4.

The base station/UE may transmit/receive the PTRS based on units of PTRSfrequency domain density (e.g., K_PT-RS in Table 7) determined based ona bandwidth (e.g., N_RB in Table 7) including RBs corresponding to thespecific TCI state. In addition, the base station/UEdefining/determining a PTRS frequency domain density maytransmit/receive the PTRS based on the PTRS frequency domain density.

If the above proposal is applied, the base station may define a PTRSfrequency domain density optimized for a size of a frequency domaincorresponding to each TRP, i.e., corresponding to each TCI state.

Embodiment 2) To determine a frequency domain density of a PTRS (i.e., afrequency density of the PTRS), a PTRS frequency domain density may bedetermined based on a bandwidth corresponding to each TCI state relatedto each TRP among all bandwidths scheduled. In other words, thefrequency domain density of the PTRS may be defined for each bandwidthcorresponding to a specific TCI state. The bandwidth corresponding tothe specific TCI state may be a resource blocks (e.g., PRB) to which thespecific TCI state is mapped.

For example, a first PTRS frequency domain density may be determined fora bandwidth corresponding to TCI state 1, and a second PTRS frequencydomain density may be determined for a bandwidth corresponding to TCIstate 2. The first PTRS frequency domain density and the second PTRSfrequency domain density may have the same vale or different values.

For example, the bandwidth corresponding to the TCI state 1 is denotedby first N_RB, and the bandwidth corresponding to the TCI state 2 isdenoted by second N_RB. By comparing thresholds (e.g., N_RB0/1)configured by a parameter frequencyDensity with the first N_RB and thesecond N_RB, the frequency density (i.e., K_PT-RS) of the PTRS may bedetermined according to the above Table 7. Specifically, if the firstN_RB/second N_RB are less than N_RB0, the PTRS may not exist. If thefirst N_RB/second N_RB are greater than or equal to N_RB0 and are lessthan N_RB1, the frequency density of the PTRS may be 2. If the firstN_RB/second N_RB are greater than or equal to N_RB1, the frequencydensity of the PTRS may be 4.

For all the frequency resources scheduled via DCI based on the ‘FRAmethod 1’ described in the proposal 1, the frequency resource of eachTRP may be determined by mapping a TCI state related to each TRP to thefrequency resource. For example, it may be assumed that a frequencyresource domain of TRP 1 is called FRG #1 and the TCI state 1 is mappedto FRG #1, and a frequency resource domain of TRP 2 is called FRG #2 andthe TCI state 2 is mapped to FRG #2. In this case, a PTRS frequencydensity (e.g., first PTRS frequency domain density) determined based ona bandwidth (e.g., first N_RB) corresponding to the TCI state 1 may beapplied in the FRG #1, and a PTRS frequency density (e.g., second PTRSfrequency domain density) determined based on a bandwidth (e.g., secondN_RB) corresponding to the TCI state 2 may be applied in the FRG #2.

If different PTRS frequency domain densities for different frequencydomains corresponding to different TCI states are determined accordingto the method of the Embodiment 2, there is an advantage of being ableto apply a PTRS frequency domain density optimized for each frequencydomain resource.

In the Embodiment 2, a parameter (e.g., frequencyDensity) fordetermining the frequency density of the PTRS is commonly configured,and the same threshold criterion has been applied to calculate thefrequency densities of the bandwidth (e.g., first N_RB) corresponding tothe TCI state 1 and the bandwidth (e.g., second N_RB) corresponding tothe TCI state 2. In addition, to define each PTRS frequency domaindensity for a bandwidth corresponding to a specific TCI state, multipleparameters for determining the frequency domain density may also bedefined. Each parameter may be applied to calculate a PTRS frequencydensity for respective bandwidths corresponding to different TCI states.

For example, a parameter frequencyDensity within PTRS-DownlinkConfigconfigured via higher layer signaling may be extended tofrequencyDensity-1/2, frequencyDensity-1 may be applied to define a PTRSfrequency domain density within a bandwidth corresponding to a first TCIstate, and frequencyDensity-2 may be applied to define a PTRS frequencydomain density within a bandwidth corresponding to a second TCI state.The base station may configure, to the UE, a plurality of parameters(e.g., frequencyDensity) for frequency density determination. Eachparameter may be used to sequentially determine the frequency density ofthe PTRS within a bandwidth corresponding to the TCI state.

Embodiment 3) To determine a frequency domain density of a PTRS (i.e., afrequency density of the PTRS), the frequency domain density of the PTRSmay be determined based on bandwidths corresponding to a half of allbandwidths scheduled via DCI among all the bandwidths scheduled via theDCI not all the bandwidths scheduled via the DCI.

For example, if the number of all the bandwidths scheduled via the DCIis odd, a specific value may be calculated through rounding operation,rounding down operation, or rounding up operation, and the frequencydomain density of the PTRS may be determined based on the calculatedbandwidth.

If the method of the Embodiment 3 is applied, there is an advantage ofbeing able to determine the frequency domain density of the PTRS througha simple fixed rule.

Embodiment 4) According to the method of the proposal 1, if frequencyresources for all TRPs are allocated to a UE via DCI and are dividedinto sub-resource groups in which scheduled frequency resources aremapped to different TCI states, a frequency domain density of a PTRS maybe defined as a specific value. The specific value may be (i) a valuedefined by a fixed rule between a base station and the UE or (ii) avalue configured via signaling (e.g., RRC/MAC-CE/DCI, etc.) between thebase station and the UE.

For example, the specific value may be configured/defined as a frequencydomain density with a smallest spacing. Referring to Table 7, thefrequency domain density with the smallest spacing may be 2. If thefrequency domain density with the smallest spacing is applied asdescribed above, there may not be a case in which a spacing at which thePTRS is transmitted in a frequency domain is greater than one PRG set tocorrespond to the same TCI state, when assuming that a size of asmallest PRG set can become 2 PRBs. Therefore, respective PTRStransmissions are possible at different TRPs.

As in the above example, when the frequency domain density of the PTRSis defined as the specific value irrespective of the number of RBsscheduled, if the number of RBs scheduled for the UE is less than thespecific value, the PTRS may not be transmitted. Considering that thefrequency domain density of the PTRS is determined depending on thenumber of RBs scheduled for the UE, there may be a disadvantage in thatdefining the frequency domain density of the PTRS as the specific valueirrespective of the number of RBs scheduled increases an unnecessary RSoverhead.

Accordingly, this embodiment can prevent a situation in which the PTRSis transmitted only in a frequency resource corresponding to a specificTRP by limiting a maximum value of the frequency domain density whilemaintaining the existing operation in which the frequency domain densityof the PTRS is determined depending on the number of RBs scheduled.

To this end, the maximum value of the frequency domain density of thePTRS may be defined as the specific value. The specific value may be (i)a value defined by the fixed rule between the base station and the UE or(ii) a value configured via signaling (e.g., RRC/MAC-CE/DCI, etc.)between the base station and the UE.

For example, the maximum value (i.e., the specific value) of thefrequency domain density of the PTRS may be 2. In this case, the maximumvalue can be prevented from being set to 4 that is a maximum spacing,and respective PTRS transmissions are possible at different TRPs.

Whether to apply the methods of the Embodiment 4 may be determineddepending on precoding granularity configured/indicated to the UE. Forexample, if the precoding granularity is configured/indicated to the UEas 4, respective PTRS transmissions are possible at different TRPs evenwhen the frequency domain density of the PTRS is determined as 4. On theother hand, if the precoding granularity is configured/indicated to theUE as 2, there may be a case in which the PTRS cannot be transmitted ata specific TRP when the frequency domain density of the PTRS isdetermined as 4. Thus, only if the precoding granularity isconfigured/indicated to the UE as 2, it can be ensured that respectivePTRS transmissions are possible at different TRPs by applying thefrequency domain density of the PTRS as the specific value to fix thefrequency domain density of the PTRS to 2 or by applying/limiting themaximum value of the frequency domain density of the PTRS to thespecific value (e.g., 2).

As described in FIG. 16 , the PTRS may be mapped to a resource elementand received. Here, the resource element may mean including at least oneof time, frequency, antenna port, or code. A frequency location of thePTRS (i.e., resource mapping of the frequency domain) may be determinedby a frequency location of associated DMRS port and a higher layerparameter UL-PTRS-RE-offset. Here, UL-PTRS-RE-offset is included in PTRSconfiguration and indicates subcarrier offset for UL PTRS for CP-OFDM.

Based on S-TRP transmission in the current standard, a transmissionlocation of the PTRS is determined based on all bandwidths scheduled viathe DCI. However, in FDM based M-TRP joint transmission, a resourcelocation of a frequency domain of the PTRS may be independentlydetermined within a bandwidth corresponding to each TCI state among allthe bandwidths scheduled via the DCI not all the bandwidths scheduledvia the DCI. That is, all the frequency resources (e.g., bandwidths)scheduled via the DCI may be divided into two or more subgroups, andrespective subgroups may correspond to different TCI states. Theresource location of the frequency domain of the PTRS may be determinedbased on the bandwidths of the subgroup corresponding to each TCI state.

In other words, in the FDM based M-TRP transmission, a plurality of(e.g., two) TCI states may be indicated via a TCI field of the DCI, andresource element mapping in the frequency domain of the PTRS may berelated to the bandwidths (e.g., PRBs) allocated for each TCI state.

For example, as described in the proposal 1, if precoding granularity is‘wideband’, all the RBGs/consecutive RBs scheduled via the DCI may beevenly allocated for each TRP (i.e., each mapped TCI state). As anexample, a bandwidth (or frequency resource) related to TCI state #1 maybe ┌X/2┐, and remaining resources ┌X/2┐−1 may be bandwidths (orfrequency resources) related to TCI state #2. Here, X may denote thenumber N_(RBG) ^(sched) of all the RBGs scheduled via the DCI, or thenumber L_(RBs) of consecutive RBs scheduled via the DCI. The PTRS may bemapped based on the bandwidths (e.g., PRBs) allocated for each TCIstate.

For example, as described in the proposal 1, if precoding granularity is‘2 or 4’, a first TCI state may correspond to an even-numbered PRG set(based on a low frequency index in the frequency resources scheduled forthe UE), and a second TCI state may correspond to an odd-numbered PRGset. The PTRS may be mapped based on the bandwidth (e.g., PRBs)allocated for each TCI state.

The method of independently determining the transmission location withinthe bandwidth corresponding to each TCI state among all the bandwidthsscheduled via the DCI may be applied to together with the method (e.g.,Embodiments 1/2/3/4) of determining the frequency domain density of thePTRS described above.

For example, based on the above-described Embodiment 2, differentfrequency domain densities may be determined within the bandwidthcorresponding to each TCI state, and the transmission location of thePTRS may be determined based on each frequency density. The basestation/UE may transmit/receive the PTRS based on units of PTRSfrequency domain density (e.g., K_PT-RS of Table 7) determined based ona bandwidth (e.g., N_RB of Table 7) including RBs corresponding to aspecific TCI state. In addition, the base station/UEdefining/determining a PTRS frequency domain density maytransmit/receive the PTRS based on the PTRS frequency domain density. Inother words, the PTRS may be mapped and received depending on afrequency density determined by the number of resource blocks(bandwidths) related to each TCI state in resource blocks (bandwidths)allocated for each TCI state.

Embodiment 5) As another example, a base station may not configure, to aUE, a combination of a frequency domain density of a PTRS and a size ofPRG and PRG set that may cause the above-mentioned problem. That is, thebase station may transmit the PTRS depending on the frequency domaindensity and a location determination method of the PTRS defined in thecurrent standard, and the UE may assume that the PTRS is transmitted ineach of resource domains corresponding to different TCI states.

According to the Embodiment 5, a PTRS frequency domain density that isnot suitable for a size of the frequency domain corresponding todifferent TRPs, i.e., corresponding to different TCI states may beapplied. For example, even in an environment where the frequency domaindensity may decrease, i.e., even in an environment where a spacing ofthe PTRS may increase in the frequency domain, a PTRS frequency domaindensity corresponding to each TRP may increase. That is, the PTRS istransmitted at a small spacing in the frequency domain corresponding toa specific TRP (or TCI state), thereby unnecessarily increasing an RSoverhead and reducing a spectral efficiency. Alternatively, on thecontrary, even in an environment where the frequency domain density hasto increase, i.e., even in an environment where the spacing of the PTRShas to decrease in the frequency domain, a PTRS frequency domain densitycorresponding to each TRP may decrease. Because the frequency domaindensity of the PTRS is calculated based on all bands scheduled via DCI,as a result, it is determined as a low density. However, the actualfrequency domain corresponding to the specific TRP (or TCI state) may beless than this, and thus may require the high frequency domain density.If the suitable PTRS frequency domain density is not supported as above,it cannot adequately compensate for impairment due to a phase noise anddegrades BLER performance, thereby reducing throughput.

The proposal method may applied to all the cases in which the precodinggranularity is 2, 4, wideband.

<Proposal 2>

Proposal 2 in which a frequency resource is configured/indicated for aspecific TRP among M-TRP operating in CoMP via single DCI as in ‘FRAmethod 2’ describe above describes a method of determining a frequencyresource for another TRP based on the configured frequency resource.

The proposal 2 also assumes a single DCI based M-TRP operation and isdescribed focusing on a situation where two TRPs operate in NCJT forconvenience of description. It is obvious that the proposal 2 can beapplied even when two or more TRPs operate.

A frequency resource for a specific TRP may be allocated to the UE via afrequency resource allocation field of DCI, and the allocated frequencyresource may be mapped to a TCI state related to a specific TRP. Forexample, a resource allocated via DCI may be a frequency resource for aTRP transmitting the DCI. A frequency resource to which a TCI staterelated to other TRP is mapped may be defined based on the frequencyresource.

For example, a difference value from a reference frequency resource(i.e., resource allocated via DCI) may be signaled (e.g., higher layersignaled/DCI signaled) to the UE, and a frequency resource of the otherTRP may be determined based on the difference value. Alternatively, thefrequency resource to which the TCI state related to the other TRP ismapped may be defined by a fixed rule between the base station and theUE.

A specific mode may be configured/indicated to the UE based on signaling(e.g., higher layer signaling/DCI signaling) and/or a rule and/or RNTIso that the UE operates according to the proposal 2. As an example, if aCRC check is successful via a specific RNTI, the DCI for frequencyresource allocation may be interpreted according to the proposed method.

For example, a rule may be defined so that it is assumed that resourcesof the same size are directly concatenated and transmitted based on aresource of a frequency domain indicated to the UE via DCI. The UE maymap a first TCI state to the resources of the frequency domain indicatedvia the DCI and map a second TCI state to the concatenated resources ofthe same size.

FIG. 18 illustrates an example of a method of determining a frequencyresource of M-TRP based on a frequency resource indicated via DCIaccording to methods described in the present disclosure. FIG. 18 ismerely an example for convenience of description and does not limit thetechnical scope of the present disclosure. Referring to FIG. 18 , afrequency resource for TRP #1 may be indicated via DCI, and TCI state #1related to the TRP #1 may be mapped to the frequency resource. Further,a frequency resource for TRP #2 may be concatenated to the frequencyresource for the TRP #1 to form the same size, and TCI state #2 relatedto the TRP #2 may be mapped to the frequency resource.

As another example, the use of some fields in the existing DCI may bechanged and applied to a use for indicating the difference value. Thebase station may signal a difference value from a resource indicated viathe frequency resource allocation field via some fields of the DCI.Examples of some fields may include some bit(s) of a field for DMRS portindication and/or some bit(s) of a field (for MCS/NDI/RV) for indicatingsecond TB information.

Based on the proposal 2, a method of defining a reference FR for TBcalculation is described.

When considering the ‘reference FR definition method 2’ for the FRAmethod 2 described in the proposal 2, i.e., only a frequency resourceallocated to a specific TRP, the current TB size calculation scheme maybe used as it is by defining partial rule for the UE operation because afrequency resource indicated via DCI is identical to a frequencyresource used for PDSCH transmission via the specific TRP. For example,if both a TB information field (for MCS1/RV1/NDI1) for a first TB and aTB information field (for MCS2/RV2/NDI2) for a second TB are used withinthe DCI, based on a specific field value, for example, based on thefirst TB information field, the TB size may be calculated based onfrequency resources scheduled via the DCI.

If only a frequency resource to which a specific TCI state is mapped isused for the TB size calculation as described above, a PDSCH transmittedvia the frequency resource applied to the TB size calculation may becalled PDSCH 1, and a PDSCH transmitted via other resource may beinterpreted as a repeatedly transmitted PDSCH and may be called PDSCH 2.In this instance, the RV and/or modulation order of the PDSCH 1 and thePDSCH 2 may be different from each other. To this end, some (e.g.,MSB(s)/LSB(s)) of the existing bits used in the field for DMRS portindication through the optimization of the DMRS table and/or the TBinformation field for indicating the MCS/RV/NDI of the second TB may bedifferently interpreted.

When considering the ‘reference FR definition method 1’ for the FRAmethod 2 described in the proposal 2, i.e., all the frequency resourcesallocated to multiple TRP, an additional UE operation is required.

Accordingly, when the UE calculates the TB size, there is proposed amethod of defining/configuring to calculate the TB size based on N timesthe frequency resource scheduled via the DCI. In this instance, N may bethe same as the number of TCI states indicated to the UE.

The UE can know the number of TRPs transmitting the PDSCH according tothe method of the proposal 2, and the number of TRPs may be the same asthe number of TCI states indicated to the UE. Accordingly, the UE canknow the size of all the frequency resources used for PDSCHtransmission. When the size of the frequency resource scheduled via DCIis denoted by B, the size of all the frequency resources is equal to theproduct of B and the number of TCI states (B*number of TCIs). Thus, theUE may define to calculate the TB size based on a frequency resourcesize obtained by multiplying the number of TCI states and B whichdenotes the size of all the frequency resources used for the PDSCHtransmission. According to the current standard, the frequency resourcesscheduled via the DCI are applied to the TB size calculation, but whenthe above method is applied, the multiple of the frequency resourcesscheduled via the DCI is applied to the TB size calculation.

Based on the frequency resource for a specific TRP allocated via one DCIin the single DCI based M-TRP operation through the methods and/orembodiments of the above-described proposal 2, a frequency resource forother TRP may be determined. A reference frequency resource for the TBsize calculation may be determined through the methods and/orembodiments of the above-described proposal 2.

Referring to the document TS 38.211, an antenna port and quasico-located (QCL) are defined as in Table 8.

TABLE 8 An antenna port is defined such that the channel over which asymbol on the antenna port is conveyed can be inferred from the channelover which another symbol on the same antenna port is conveyed. ForDM-RS associated with a PDSCH, the channel over which a PDSCH symbol onone antenna port is conveyed can be inferred from the channel over whicha DM-RS symbol on the same antenna port is conveyed only if the twosymbols are within the same resource as the scheduled PDSCH, in the sameslot, and in the same PRG as described in clause 5.1.2.3 of [6, TS38.214]. Two antenna ports are said to be quasi co-located if thelarge-scale properties of the channel over which a symbol on one antennaport is conveyed can be inferred from the channel over which a symbol onthe other antenna port is conveyed. The large-scale properties includeone or more of delay spread, Doppler spread, Doppler shift, averagegain, average delay, and spatial Rx parameters.

In order to apply the above-described methods and/or embodiments (e.g.,proposal 1/proposal 1-1/proposal 2, etc.), the QCL definition of FIG. 8may be partially modified as shown Table 9. The modified part is thepart marked with an underline.

TABLE 9 Two antenna ports are said to be quasi co-located(with respect to the specific RB set) if the large-scale properties ofthe channel over which a symbol on one antenna portwithin a same QCL-f-RB set is conveyed can be inferred from the channelover which a symbol on the other antenna port is conveyed. Thelarge-scale properties include one or more of delay spread, Dopplerspread, Doppler shift, average gain, average delay, and spatial Rxparameters.

Referring to Table 9, “QCL-f-RB set” may mean an RB set (a set offrequency resources) that may assume/apply the same QCL reference RS(and/or antenna port) for a target antenna port. The number ofcontiguous RBs within the RB set may be equal to or greater than the PRGsize. The proposed methods and/or embodiments (e.g., proposal 1/proposal1-1/proposal 2, etc.) described above may be seen an example of a methodof constructing the QCL-f-RB set. That is, according the proposedmethods and/or embodiments (e.g., proposal 1/proposal 1-1/proposal 2,etc.) described above, a frequency resource to which a specific TCIstate is mapped may be determined, and the frequency resource to whichthe specific TCI state is mapped may correspond to the QCL-f-RB set.

In the proposed methods and/or embodiments (e.g., proposal 1/proposal1-1/proposal 2, etc.) described above, it may be defined so that theproposed method is applied to frequency resources to be mapped to TCIstates related to different TRPs in a specific unit (VRB or PRB) among avirtual resource block (VRB) or a physical resource block (PRB).Alternatively, it may be defined to select the unit (VRB or PRB) towhich the proposal is applied through signaling (e.g., higher layersignaling/DCI) and/or a rule.

In the methods and/or embodiments (e.g., proposal 1/proposal1-1/proposal 2, etc.) described in the present disclosure, the jointtransmission operation of two different TRPs has been assumed, but themethods and/or embodiments described in the present disclosure can beapplied to multiple, e.g., three or more TRPs. The proposed methodsand/or embodiments (e.g., proposal 1/proposal 1-1/proposal 2, etc.)described above have been described based on multiple TRPs, but can beequally applied to transmission across multiple panel. The methodsand/or embodiments (e.g., proposal 1/proposal 1-1/proposal 2, etc.)described in the present disclosure have been described focusing on thesingle DCI based M-TRP transmission, but can be applied to the multipleDCI based M-TRP transmission/reception transmitting DCI in remainingTRPs excluding some TRPs of multiple TRPs.

FIG. 19 illustrates signaling when a UE receives single DCI (i.e., whena representative TRP transmits DCI to the UE) in a situation of M-TRP(or M-cell, hereinafter all TRPs may be replaced with cells, or casewhere multiple CORERSETs (/CORESET groups) are configured from one TRPmay be assumed as M-TRP). FIG. 19 is merely an example for convenienceof description and does not limit the technical scope of the presentdisclosure.

Although the following description will be given with respect to “TRP”,“TRP” may be replaced with other expressions such as a panel, an antennaarray, a cell (e.g., macro cell/small cell/pico cell), a TP(transmission point), and a base station (gNB). Also, as describedabove, the TRPs may be divided according to information (e.g., index,ID) on a CORESET group (or CORESET pool). For example, if one UE isconfigured to perform transmission and reception to and from multipleTRPs (or cells), this may mean that multiple CORESET groups (or CORESETpools) are configured for one UE. Such a configuration for CORESETgroups (or CORESET pools) may be performed via higher layer signaling(e.g., RRC signaling).

Referring to FIG. 19 , signaling between two TRPs and the UE isconsidered for the convenience of explanation, but this signaling methodcan be extendedly applied to signaling between multiple TRPs andmultiple UEs. In the description below, a network side may be a basestation including a plurality of TRPs or a cell including a plurality ofTRPs. For example, ideal/non-ideal backhaul may be configured betweenTRP 1 and TRP 2 constituting the network side. Further, the descriptionbelow is described based on multiple TRPs, but this can be extendedlyapplied to transmission through multiple panels. In addition, in thepresent disclosure, an operation for a UE to receive a signal fromTRP1/TRP2 may be interpreted/described as (or may be) an operation forthe UE to receive a signal from the network side (through/usingTRP1/TRP2), and an operation for the UE to transmit a signal toTRP1/TRP2 may be interpreted/described as (or may be) an operation forthe UE to transmit a signal to the network side (through/usingTRP1/TRP2), and they may be interpreted/described in an inversed manner.

The UE may receive configuration information related to multipleTRP-based transmission and reception through/using TRP 1 (and/or TRP 2)from a network side (S1905). That is, the network side may transmitconfiguration information related to multiple TRP transmission andreception to the UE through/using TRP 1 (and/or TRP 2) (S1905). Theconfiguration information may include information related to theconfiguration of the network side (i.e., TRP configuration), resourceinformation related to multiple TRP-based transmission and reception(resource allocation), and so on. The configuration information may bedelivered through higher-layer signaling (e.g., RRC signaling, MAC-CE,etc.). Also, if the configuration information is predefined or preset,the corresponding step may be omitted.

For example, the configuration information may include CORESET relatedconfiguration information (e.g., ControlResourceSet IE) as described inthe above-described methods (e.g., proposal 1/proposal 1-1/proposal 2,etc.). The CORESET related configuration information may include aCORESET related ID (e.g., controlResourceSetID), an index of a CORESETpool for CORESET (e.g., CORESETPoolIndex), time/frequency resourceconfiguration of CORESET, TCI information related to CORESET, and thelike. The index of the CORESET pool (e.g., CORESETPoolIndex) may mean aspecific index (e.g., CORESET group Index, HARQ Codebook index)mapped/configured to each CORESET.

For example, according to the above-described methods and/or embodiments(e.g., proposal 1/proposal 1-1/proposal 2), the configurationinformation may include information about which one of multiple URLLCoperations is to be performed. For example, the configurationinformation may include information configuring one of M-TRP URLLCschemes (e.g., scheme 2a/2b/3/4).

For example, the configuration information may include PTRS relatedconfiguration information. The PTRS related configuration information(e.g., PTRS-DownlinkConfig) may include information for a frequencydensity (e.g., frequencyDensity parameter), information for a timedensity (e.g., timeDensity parameter), epre-Ratio parameter, a resourceelement offset parameter (e.g., resourceElementOffset), etc. of thePTRS.

For example, in the above step S1905, an operation in which the UE(100/200 of FIGS. 21 to 25 ) receives configuration information relatedto the multiple TRP-based transmission and reception from the networkside (100/200 of FIGS. 21 to 25 ) may be implemented by an apparatus ofFIGS. 21 to 25 to be described below. For example, referring to FIG. 22, one or more processors 102 may control one or more transceivers 106and/or one or more memories 104 to receive the configuration informationrelated to the multiple TRP-based transmission and reception, and one ormore transceivers 106 may receive the configuration information relatedto the multiple TRP-based transmission and reception from the networkside.

Similarly, in the above step S1905, an operation in which the networkside (100/200 of FIGS. 21 to 25 ) transmits configuration informationrelated to the multiple TRP-based transmission and reception to the UE(100/200 of FIGS. 21 to 25 ) may be implemented by an apparatus of FIGS.21 to 25 to be described below. For example, referring to FIG. 22 , oneor more processors 102 may control one or more transceivers 106 and/orone or more memories 104 to transmit the configuration informationrelated to the multiple TRP-based transmission and reception, and theconfiguration information related to the multiple TRP-based transmissionand reception is transmitted, by one or more transceivers 106, from thenetwork side.

The UE may receive DCI and Data 1 scheduled by the DCI through/using TRP1 from the network side (S1910-1). The UE may receive Data 2through/using TRP 2 from the network side (S1910-2). That is, thenetwork side may transmit DCI and Data scheduled by the DCI to the UEthrough/using TRP 1 (S1910-1). The network side may also transmit Data 2to the UE through/using TRP 2 (S1910-2). For example, DCI and Data(e.g., Data 1, Data 2) may be transmitted via a control channel (e.g.,PDCCH, etc.) and a data channel (e.g., PDSCH, etc.). Further, the stepsS1910-1 and S1910-2 may be performed simultaneously, or one of the stepsS1910-1 and S1910-2 may be performed earlier than the other.

For example, the DCI may include a TCI field, antenna port(s) field, atime domain resource assignment field, a frequency domain resourceassignment field, an MCS field or an RV field, etc.

For example, as described in the above-described methods and/orembodiments (e.g., proposal 1/proposal 1-1/proposal 2), the DCI may beconfigured to be used for scheduling for both Data 1 and Data 2, and theData 1 and the Data 2 may correspond to the same TB.

For example, on the assumption that non-overlapping frequency resourcesare used, the DCI may include information for a mapping relationshipbetween the frequency resources and TCI states related to different TRPs(e.g., TRP 1, TRP 2). Through this, the UE may understand a mappingrelationship between the frequency resource and the TCI state/TRP. Forthe DCI, the UE may be configured to calculate the TB size (i.e., tointerpret a TB related information field) based on a frequency resourceaccording to a predetermined criterion.

For example, as in the above-described proposal 1-1, the frequencydensity/frequency resource mapping of the PTRS may be determined basedon the DCI. If the frequency resources scheduled via the DCI are mappedto different TCI states, the frequency density/frequency resourcemapping of the PTRS may be determined depending on a frequency resource(e.g., bandwidth/PRBs) related to each TCI state. Further, in this case,Data 1 and Data 2 may be transmitted and received based on PTRS (port),etc. described in the proposal 1-1.

For example, an operation for the UE (100/200 of FIGS. 21 to 25 ) of thesteps S1910-1/S1910-2 to receive the DCI and/or the Data 1 and/or theData 2 from the network side (100/200 of FIGS. 21 to 25 ) may beimplemented by the device of FIGS. 21 to 25 to be described below.

For example, referring to FIG. 22 , one or more processors 102 maycontrol one or more transceivers 106 and/or one or more memories 104 soas to receive the DCI and/or the Data 1 and/or the Data 2, and the oneor more transceivers 106 may receive the DCI and/or the Data 1 and/orthe Data 2 from the network side.

Similar to this, an operation for the network side (100/200 of FIGS. 21to 25 ) of the steps S1910-1/S1910-2 to transmit the DCI and/or the Data1 and/or the Data 2 to the UE (100/200 of FIGS. 21 to 25 ) may beimplemented by the device of FIGS. 21 to 25 to be described below. Forexample, referring to FIG. 22 , one or more processors 102 may controlone or more transceivers 106 and/or one or more memories 104 so as totransmit the DCI and/or the Data 1 and/or the Data 2, and the one ormore transceivers 106 may transmit the DCI and/or the Data 1 and/or theData 2 to the UE.

The UE may decode the Data 1 and/or the Data 2 receiving from TRP 1 andTRP 2 (S1915). For example, the UE may perform decoding on channelestimation and/or data based on the above-described methods (e.g.,proposal 1/proposal 1-1/proposal 2, etc).

For example, based on the above-described proposed methods and/orembodiments (e.g., proposal 1/proposal 2/proposal 3/proposal 4, etc.),the UE can know that the base station has transmitted the same dataaccording to a specific URLLC operation, and may assume that the Data 1and the Data 2 are the same TB to decode the Data 1 and the Data 2. Asan example, the UE may assume that the base station has repeatedlytransmitted the same data as many as the number of TCI states indicatedvia the DCI and may decode the Data 1 and the Data 2. For example, theUE may assume that the base station has repeatedly transmitted the samedata in the frequency domain indicated via the DCI and may decode theData 1 and the Data 2.

For example, an operation for the UE (100/200 of FIGS. 21 to 25 ) of thestep S1915 to decode the Data 1 and the Data 2 may be implemented by thedevice of FIGS. 21 to 25 to be described below. For example, referringto FIG. 22 , one or more processors 102 may control one or more memories104 so as to decode the Data 1 and the Data 2.

Based on the above-described proposal methods (e.g., proposal 1/proposal1-1/proposal 2, etc), the UE may transmit HARQ-ACK information (e.g.,ACK information, NACK information, etc.) for the DCI and/or the Data 1and/or the Data 2 on one or more PUCCHs to the network sidethrough/using TRP 1 and/or TRP 2 (S1920-1, S1920-2). That is, based onthe above-described proposal methods (e.g., proposal 1/proposal1-1/proposal 2, etc), the network side may receive HARQ-ACK information(e.g., ACK information, NACK information, etc.) for the DCI and/or theData 1 and/or the Data 2 from the UE through/using TRP 1 and/or TRP 2(S1920-1, S1920-2).

For example, HARQ-ACK information for the Data 1 and/or the Data 2 maybe combined into one or separated. The UE may be configured to transmitonly HARQ-ACK information as a representative TRP (e.g., TRP 1), andtransmission of HARQ-ACK information to another TRP (e.g., TRP 2) may beomitted. For example, the HARQ-ACK information may be transmitted viaPUCCH and/or PUSCH.

For example, an operation for the UE (100/200 of FIGS. 21 to 25 ) of thesteps S1920-1/S1920-2 to transmit HARQ-ACK information for the Data 1and/or the Data 2 to the network side (100/200 of FIGS. 21 to 25 ) onone or more PUCCHs may be implemented by the device of FIGS. 21 to 25 tobe described below. For example, referring to FIG. 22 , one or moreprocessors 102 may control one or more transceivers 106 and/or one ormore memories 104 so as to transmit HARQ-ACK information for the Data 1and/or the Data 2 on one or more PUCCHs, and the one or moretransceivers 106 may transmit the HARQ-ACK information for the Data 1and/or the Data 2 to the network side.

Similar to this, an operation for the network side (100/200 of FIGS. 21to 25 ) of the steps S1920-1/S1920-2 to receive HARQ-ACK information forthe Data 1 and/or the Data 2 from the UE (100/200 of FIGS. 21 to 25 ) onone or more PUCCHs may be implemented by the device of FIGS. 21 to 25 tobe described below. For example, referring to FIG. 22 , one or moreprocessors 102 may control one or more transceivers 106 and/or one ormore memories 104 so as to receive HARQ-ACK information for the Data 1and/or the Data 2, and the one or more transceivers 106 may receive theHARQ-ACK information for the Data 1 and/or the Data 2 from the UE.

FIG. 19 illustrates mainly the single-DCI based M-TRP operation, but canbe applied to a multiple DCI based M-TRP operation, if necessary ordesired.

FIG. 20 illustrates an example of a flow chart of a PTRS receptionoperation of a user equipment (UE) to which methods (e.g., proposal1/proposal 1-1/proposal 2, etc.) described in the present disclosure areapplicable. The UE can be supported by a plurality of TRPs, andideal/non-ideal backhaul may be configured between the plurality ofTRPs. For example, the UE may include one or more transceivers, one ormore processors, and one or more memories that store instructions foroperations executed by the one or more processors and are connected tothe one or more processors. FIG. 20 is merely an example for convenienceof description and does not limit the scope of the present disclosure.Some step(s) illustrated in FIG. 20 may also be omitted depending oncircumstances and/or configurations, etc.

Although the following description will be given based on the “TRP”, asdescribed above, the “TRP” may be applied by being replaced byexpressions such as a panel, an antenna array, a cell (e.g., macrocell/small cell/pico cell, etc.), a transmission point (TP), and a basestation (e.g., gNB, etc.). Further, as described above, the TRP may bedivided according to information (e.g., index, ID) for a CORESET group(or CORESET pool). For example, if one UE is configured to performtransmission and reception with multiple TRPs (or cells), this may meanthat multiple CORESET groups (or CORESET pools) are configured to theone UE. The above-described configuration for the CORESET groups (orCORESET pools) may be performed via higher layer signaling (e.g., RRCsignaling, etc.).

In performing the operation of FIG. 20 , it may be assumed that the UEis supported by FDM based M-TRPs. It may also be assumed that a codepoint mapped to a plurality of TCI states (e.g., TCI state 1 and TCIstate 2) is configured to the UE via a TCI field of DCI.

The UE may receive PTRS configuration information, in S2010. Forexample, the PTRS configuration information may be received via RRCsignaling.

For example, the PTRS configuration information may refer toPTRS-DownlinkConfig IE. The PTRS configuration information (e.g.,PTRS-DownlinkConfig) may include information for a frequency density(e.g., frequencyDensity parameter), information for a time density(e.g., timeDensity parameter), epre-Ratio parameter, a resource elementoffset parameter (e.g., resourceElementOffset), etc. of the PTRS. Forexample, the information for the frequency density of the PTRS (i.e.,frequency density parameter) may include thresholds (e.g., a firstthreshold and a second threshold) of a bandwidth for determining thefrequency density of the PTRS. As an example, considering M-TRPtransmission, each of the first threshold and the second threshold maybe set as a plurality of values. In other words, the thresholds fordetermining the frequency density of the PTRS for each TRP may bedifferently set.

For example, an operation of the UE (100/200 of FIGS. 22 to 26 ) in thestep S2010 to receive the PTRS configuration information may beimplemented by a device of FIGS. 22 to 26 to be described below. Forexample, referring to FIG. 23 , one or more processors 102 may controlone or more transceivers 106 and/or one or more memories 104 so as toreceive the PTRS configuration information, and the one or moretransceivers 106 may receive the PTRS configuration information.

The UE may receive downlink control information (DCI), in S2020. The DCImay be transmitted via a control channel (e.g., PDCCH).

The DCI may include at least one of i) a transmission configurationindication (TCI) field, ii) an antenna port field, or iii) a frequencyresource assignment field.

For example, code points corresponding to one or more TCI states may beindicated based on the TCI field. For example, code points to which aplurality of TCI states (e.g., TCI state 1 and TCI state 2) are mappedmay be configured/indicated based on the TCI field of the DCI.

For example, a plurality of state information related to a combinationof the number of CDM groups without data and DMRS ports may bepredefined, and specific state information (or value) of the pluralityof state information may be indicated via an antenna port field of theDCI. As an example, the state information may mean DMRS port relatedinformation (e.g., 3GPP TS38.212 Table 7.3.1.2.2-1/2/3/4, etc.). Amapping relationship between the DMRS ports and the CDM groups may bepredefined. The DMRS ports and the number of CDM groups including theDMRS ports may be determined through the indicated specific stateinformation (or value). For example, the DMRS ports of the same CDMgroup may be indicated based on the antenna port field.

For example, frequency resources for all the M-TRPs operating in NCJTmay be allocated based on the frequency resource assignment field (e.g.,third field) (e.g., FRA method 1). All the frequency resources allocatedbased on the above-described proposed methods and/or embodiments (e.g.,proposal 1/proposal 1-1/proposal 1-2, etc.) may be divided and allocatedfor each TRP. For example, all the frequency resources assigned on a perPRG or PRG set basis may be divided. If precoding granularity isconfigured/indicated to the UE as 2 or 4, even-numbered PRGs/PRG sets(e.g., first region) may be allocated to TRP 1, and odd-numberedPRGs/PRG sets (e.g., second region) may be allocated to TRP 2. Asanother example, all the frequency resources assigned on a per RB or RBset basis may be divided. If precoding granularity isconfigured/indicated to the UE as wideband, resources may be divided byfloor (all the allocated resources/2) to evenly distribute resources foreach TRP.

A plurality of TCI states indicated via the TCI field of DCI may bemapped to the frequency resource domain assigned based on the frequencyresource assignment field. For example, the assigned frequency resourcedomain may include a first region and a second region that do notoverlap in the frequency domain. That is, the frequency resource domainassigned via DCI may be divided into the first region and the secondregion. The first region may be related to a first TCI state, and thesecond region may be related to a second TCI state. In this case, afirst frequency density of the PTRS may be determined by the number ofresource blocks in the first region, and a second frequency density ofthe PTRS may be determined by the number of resource blocks in thesecond region.

For example, if frequency resources for all the M-TRPs operating in NCJTare allocated based on the frequency resource assignment field, andfrequency resources for specific TRPs need to be considered to calculatea TB size, the frequency resources for the specific TRPs for the TB sizecalculation may be indicated from the base station or determined by apredefined rule.

As another example, a frequency resource for a specific TRP among theM-TRPs operating in NCJT may be assigned based on the frequency resourceassignment field (e.g., FRA method 2). A frequency resource for otherTRP performing the NCJT based on the frequency resource assigned for thespecific TRP may be determined based on the above-described proposedmethods and/or embodiments (e.g., proposal 1/proposal 1-1/proposal 1-2,etc.). For example, the frequency resource for the other TRP may havethe same size as a resource assigned via DCI and may be assigned bybeing concatenated with the resource assigned via DCI. Alternatively, adifference value from the resource assigned via DCI may be configuredvia separate signaling (e.g., DCI).

For example, when a frequency resource for a specific TRP among theM-TRPs operating in NCJT is assigned based on the frequency resourceassignment field, and a frequency resource for other TRP uses theresource assigned via DCI, if frequency resources for all the TRPs needto be considered to calculate the TB size, the TB size may be calculatedusing a frequency resource size obtained by multiplying the resourcesize scheduled via DCI by the number of TCI states.

For example, an operation of the UE (100/200 of FIGS. 22 to 26 ) in thestep S2020 to receive the downlink control information (DCI) may beimplemented by the device of FIGS. 22 to 26 to be described below. Forexample, referring to FIG. 23 , one or more processors 102 may controlone or more transceivers 106 and/or one or more memories 104 so as toreceive the DCI, and the one or more transceivers 106 may receive theDCI.

The UE may receive the PTRS based on the DCI, in 52030. The PTRS may bereceived via an antenna port (e.g., PTRS port). The antenna portreceiving the PTRS may mean a resource element via which the PTRS istransmitted/received.

For example, the PTRS may be mapped to time and/or frequency resourceand received. The PTRSs may be mapped to the resource element at apredetermined spacing in the frequency domain. The spacing (e.g., thenumber of RBs) between the PTRSs may mean the frequency density of thePTRS. The frequency density of the PTRS may be determined depending on ascheduled bandwidth.

For example, in a single TRP transmission, the PTRS frequency densitymay be determined based on bandwidths of all the frequency domainsscheduled via the DCI. On the other hand, in an M-TRP transmission,based on a plurality of TCI states being indicated based on the DCI andnon-overlapping resources in a frequency domain related to each TCIstate of the plurality of TCI states, the frequency density of the PTRSmay be determined by the number of resource blocks related to each TCIstate.

As a detailed example, the frequency density of the PTRS may bedetermined by comparing at least one of thresholds (e.g., a firstthreshold and a second threshold) set through the information for thefrequency density of the PTRS with the number of resource blocks relatedto each TCI state. For example, a first frequency density of the PTRSmay be determined by the number of resource blocks of a resource region(e.g., a first region) related to the first TCI state, and a secondfrequency density of the PTRS may be determined by the number ofresource blocks of a resource region (e.g., a second region) related tothe second TCI state. In the first region, the PTRS may be mapped to aresource element based on the first frequency density and received, andin the second region, the PTRS may be mapped to a resource element basedon the second frequency density and received.

The UE can perform compensation for a phase noise using the receivedPTRS.

For example, an operation of the UE (100/200 of FIGS. 22 to 26 ) in thestep S2040 to receive the PTRS may be implemented by the device of FIGS.22 to 26 to be described below. For example, referring to FIG. 23 , oneor more processors 102 may control one or more transceivers 106 and/orone or more memories 104 so as to receive the PTRS, and the one or moretransceivers 106 may receive the PTRS.

FIG. 21 illustrates an example of a flow chart of a PTRS transmissionoperation of a base station (BS) to which methods (e.g., proposal1/proposal 1-2/proposal 3, etc.) described in the present disclosure areapplicable. FIG. 21 is merely an example for convenience of descriptionand does not limit the scope of the present disclosure. Some step(s)illustrated in FIG. 21 may also be omitted depending on circumstancesand/or configurations, etc.

The base station may mean a generic term for an object performingtransmission and reception of data together with the UE. For example,the base station may include one or more transceivers, one or moreprocessors, and one or more memories that store instructions foroperations executed by the one or more processors and are connected tothe one or more processors. For example, the base station may be aconcept including one or more transmission points (TPs), one or moretransmission and reception points (TRPs), etc. The TP and/or the TRP mayinclude a panel, a transmission and reception unit, etc. of the basestation. As described above, the TRP may be divided according toinformation (e.g., index, ID) for a CORESET group (or CORESET pool). Forexample, if one UE is configured to perform transmission and receptionwith multiple TRPs (or cells), this may mean that multiple CORESETgroups (or CORESET pools) are configured to the one UE. Theabove-described configuration for the CORESET groups (or CORESET pools)may be performed via higher layer signaling (e.g., RRC signaling, etc.).

The base station may transmit PTRS configuration information to a UE, inS2110. For example, the PTRS configuration information may betransmitted via RRC signaling.

For example, the PTRS configuration information may refer toPTRS-DownlinkConfig IE. The PTRS configuration information (e.g.,PTRS-DownlinkConfig) may include information for a frequency density(e.g., frequencyDensity parameter), information for a time density(e.g., timeDensity parameter), epre-Ratio parameter, a resource elementoffset parameter (e.g., resourceElementOffset), etc. of the PTRS. Forexample, the information for the frequency density of the PTRS (i.e.,frequency density parameter) may include thresholds (e.g., a firstthreshold and a second threshold) of a bandwidth for determining thefrequency density of the PTRS. As an example, considering M-TRPtransmission, each of the first threshold and the second threshold maybe set as a plurality of values. In other words, the thresholds fordetermining the frequency density of the PTRS for each TRP may bedifferently set.

For example, an operation of the base station (100/200 of FIGS. 22 to 26) in the step S2110 to transmit the PTRS configuration information maybe implemented by a device of FIGS. 22 to 26 to be described below. Forexample, referring to FIG. 23 , one or more processors 102 may controlone or more transceivers 106 and/or one or more memories 104 so as totransmit the PTRS configuration information, and the one or moretransceivers 106 may transmit the PTRS configuration information to theUE.

The base station may transmit downlink control information (DCI) to theUE, in S2120. The DCI may be transmitted via a control channel (e.g.,PDCCH).

The DCI may include at least one of i) a transmission configurationindication (TCI) field, ii) an antenna port field, or iii) a frequencyresource assignment field.

For example, code points corresponding to one or more TCI states may beindicated based on the TCI field. For example, code points to which aplurality of TCI states (e.g., TCI state 1 and TCI state 2) are mappedmay be configured/indicated based on the TCI field of the DCI.

For example, the DMRS ports of the same CDM group may be indicated basedon the antenna port field.

For example, frequency resources allocated for all the M-TRPs operatingin NCJT may be indicated based on the frequency resource assignmentfield (e.g., FRA method 1). All the frequency resources allocated basedon the above-described proposed methods and/or embodiments (e.g.,proposal 1/proposal 1-1/proposal 1-2, etc.) may be divided and allocatedfor each TRP. As another example, a frequency resource for a specificTRP among the M-TRPs operating in NCJT may be indicated based on thefrequency resource assignment field (e.g., FRA method 2). A frequencyresource for other TRP performing the NCJT based on the frequencyresource assigned for the specific TRP may be determined based on theabove-described proposed methods and/or embodiments (e.g., proposal1/proposal 1-1/proposal 1-2, etc.).

For example, an operation of the base station (100/200 of FIGS. 22 to 26) in the step S2120 to transmit the downlink control information (DCI)may be implemented by the device of FIGS. 22 to 26 to be describedbelow. For example, referring to FIG. 23 , one or more processors 102may control one or more transceivers 106 and/or one or more memories 104so as to transmit the DCI, and the one or more transceivers 106 maytransmit the DCI to the UE.

The base station may transmit the PTRS to the UE, in S2130. The PTRS maybe sued to perform compensation for a phase noise. Specifically, thebase station may generate a sequence used for the PTRS and map thegenerated PTRS sequence to a resource element to transmit the PTRS. Thebase station may map the PTRS sequence to a time resource, a frequencyresource, or time and frequency resources to transmit the PTRS.

For example, the frequency resource domain assigned based on thefrequency resource assignment field of the DCI may be divided(distinguished) into a plurality of regions (e.g., a first region and asecond region) in the FDM scheme. The respective plurality of regionsmay not overlap and may correspond to TCI states indicated via the TCIfield. As an example, the first region may be related to a first TCIstate, and the second region may be related to a second TCI state. Theresource element mapping of the PTRS in the frequency domain may berelated to resource blocks assigned for each TCI state.

For example, a pattern of the PTRS may be determined depending on adensity of a frequency domain and a density of a time domain. Thefrequency density of the PTRS may mean a spacing between the PTRSs(e.g., the number of RBs) in the frequency domain. The density of thetime domain (i.e., the time density of the PTRS) may mean a spacingbetween the PTRSs (e.g., the number of symbols) in the time domain.

As a detailed example, based on a plurality of TCI states beingindicated based on the DCI and non-overlapping resources in a frequencydomain related to each TCI state of the plurality of TCI states, thefrequency density of the PTRS may be determined by the number ofresource blocks related to each TCI state. The frequency density of thePTRS may be determined by comparing at least one of thresholds (e.g., afirst threshold and a second threshold) set through the information forthe frequency density of the PTRS with the number of resource blocksrelated to each TCI state.

For example, a first frequency density of the PTRS may be determined bythe number of resource blocks of a resource region (e.g., first region)related to the first TCI state, and a second frequency density of thePTRS may be determined by the number of resource blocks of a resourceregion (e.g., second region) related to the second TCI state. The basestation may map the PTRS to a resource element based on the firstfrequency density in the first region and map the PTRS to a resourceelement based on the second frequency density in the second region totransmit the PTRS.

For example, an operation of the base station (100/200 of FIGS. 22 to 26) in the step S2130 to transmit the PTRS to the UE may be implemented bythe device of FIGS. 22 to 26 to be described below. For example,referring to FIG. 23 , one or more processors 102 may control one ormore transceivers 106 and/or one or more memories 104 so as to transmitthe PTRS, and the one or more transceivers 106 may transmit the PTRS tothe UE.

As mentioned above, the above-described network side/UE signaling andoperation (e.g., the proposal 1/proposal 1-1/proposal 2/FIG. 19 /FIG. 20/FIG. 21 , etc.) may be implemented by a device to be described below(e.g., FIGS. 22 to 26 ). For example, the network side (e.g., TRP 1/TRP2) may correspond to a first wireless device, and the UE may correspondto a second wireless device. In some cases, the reverse may also beconsidered. For example, a first device (e.g., TRP 1)/second device(e.g., TRP 2) may correspond to a first wireless device, and the UE maycorrespond to a second wireless device. In some cases, the reverse mayalso be considered.

For example, the above-described network side/UE signaling and operation(e.g., the proposal 1/proposal 1-1/proposal 2/FIG. 19 /FIG. 20 /FIG. 21, etc.) may be processed by one or more processors (e.g., 102 and 202)of FIGS. 22 to 26 . The above-described network side/UE signaling andoperation (e.g., the proposal 1/proposal 1-1/proposal 2/FIG. 19 /FIG. 20/FIG. 21 , etc.) may be stored in one or more memories (e.g., 104 and204) in the form of a command/program (e.g., instruction, executablecode) for running at least one processor (e.g., 102 and 202) of FIGS. 22to 26 .

For example, in a device comprising one or more memories and one or moreprocessors operatively connected to the one or more memories accordingto an embodiment of the present disclosure, wherein the one or moreprocessors are configured to allow the device to receive PTRSconfiguration information, receive downlink control information (DCI),and receive the PTRS. The PTRS configuration information includesinformation for a frequency density of the PTRS, wherein a plurality ofTCI states are indicated based on the DCI, and wherein based onnon-overlapping resources in a frequency domain related to each TCIstate of the plurality of TCI states, the frequency density of the PTRSis determined by a number of resource blocks related to each TCI state.

For example, in one or more non-transitory computer readable mediumsstoring one or more instructions according to an embodiment of thepresent disclosure, the one or more instructions executable by one ormore processors may allow a user equipment (UE) to receive PTRSconfiguration information, receive downlink control information (DCI),and receive the PTRS. The PTRS configuration information includesinformation for a frequency density of the PTRS, wherein a plurality ofTCI states are indicated based on the DCI, and wherein based onnon-overlapping resources in a frequency domain related to each TCIstate of the plurality of TCI states, the frequency density of the PTRSis determined by a number of resource blocks related to each TCI state.

Communication System Applied to the Present Disclosure

The various descriptions, functions, procedures, proposals, methods,and/or operational flowcharts of the present disclosure described inthis document may be applied to, without being limited to, a variety offields requiring wireless communication/connection (e.g., 5G) betweendevices.

Hereinafter, a description will be given in more detail with referenceto the drawings. In the following drawings/description, the samereference symbols may denote the same or corresponding hardware blocks,software blocks, or functional blocks unless described otherwise.

FIG. 22 illustrates a communication system 1 applied to the presentdisclosure.

Referring to FIG. 22 , a communication system 1 applied to the presentdisclosure includes wireless devices, Base Stations (BSs), and anetwork. Herein, the wireless devices represent devices performingcommunication using Radio Access Technology (RAT) (e.g., 5G New RAT(NR)) or Long-Term Evolution (LTE)) and may be referred to ascommunication/radio/5G devices. The wireless devices may include,without being limited to, a robot 1010 a, vehicles 1010 b-1 and 1010b-2, an eXtended Reality (XR) device 1010 c, a hand-held device 1010 d,a home appliance 1010 e, an Internet of Things (IoT) device 1010 f, andan Artificial Intelligence (AI) device/server 400. For example, thevehicles may include a vehicle having a wireless communication function,an autonomous driving vehicle, and a vehicle capable of performingcommunication between vehicles. Herein, the vehicles may include anUnmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may includean Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) deviceand may be implemented in the form of a Head-Mounted Device (HMD), aHead-Up Display (HUD) mounted in a vehicle, a television, a smartphone,a computer, a wearable device, a home appliance device, a digitalsignage, a vehicle, a robot, etc. The hand-held device may include asmartphone, a smartpad, a wearable device (e.g., a smartwatch orsmartglasses), and a computer (e.g., a notebook). The home appliance mayinclude a TV, a refrigerator, and a washing machine. The IoT device mayinclude a sensor and a smartmeter. For example, the BSs and the networkmay be implemented as wireless devices and a specific wireless device200 a may operate as a BS/network node with respect to other wirelessdevices.

The wireless devices 1010 a to 1010 f may be connected to the network300 via the BSs 1020. An AI technology may be applied to the wirelessdevices 1010 a to 1010 f and the wireless devices 1010 a to 1010 f maybe connected to the AI server 400 via the network 300. The network 300may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G(e.g., NR) network. Although the wireless devices 1010 a to 1010 f maycommunicate with each other through the BSs 1020/network 300, thewireless devices 1010 a to 1010 f may perform direct communication(e.g., sidelink communication) with each other without passing throughthe BSs/network. For example, the vehicles 1010 b-1 and 1010 b-2 mayperform direct communication (e.g. Vehicle-to-Vehicle(V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g.,a sensor) may perform direct communication with other IoT devices (e.g.,sensors) or other wireless devices 1010 a to 1010 f.

Wireless communication/connections 150 a, 150 b, or 150 c may beestablished between the wireless devices 1010 a to 1010 f/BS 1020, or BS1020/BS 1020. Herein, the wireless communication/connections may beestablished through various RATs (e.g., 5G NR) such as uplink/downlinkcommunication 150 a, sidelink communication 150 b (or, D2Dcommunication), or inter BS communication (e.g. Relay, Integrated AccessBackhaul(IAB)). The wireless devices and the BSs/the wireless devicesmay transmit/receive radio signals to/from each other through thewireless communication/connections 150 a and 150 b. For example, thewireless communication/connections 150 a and 150 b may transmit/receivesignals through various physical channels. To this end, at least a partof various configuration information configuring processes, varioussignal processing processes (e.g., channel encoding/decoding,modulation/demodulation, and resource mapping/demapping), and resourceallocating processes, for transmitting/receiving radio signals, may beperformed based on the various proposals of the present disclosure.

Devices Applicable to the Present Disclosure

FIG. 23 illustrates wireless devices applicable to the presentdisclosure.

Referring to FIG. 23 , a first wireless device 100 and a second wirelessdevice 200 may transmit radio signals through a variety of RATs (e.g.,LTE and NR). Herein, {the first wireless device 100 and the secondwireless device 200} may correspond to {the wireless device 1010 x andthe BS 1020} and/or {the wireless device 1010 x and the wireless device1010 x} of FIG. 22 .

The first wireless device 100 may include one or more processors 102 andone or more memories 104 and additionally further include one or moretransceivers 106 and/or one or more antennas 108. The processor(s) 102may control the memory(s) 104 and/or the transceiver(s) 106 and may beconfigured to implement the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. For example, the processor(s) 102 may process informationwithin the memory(s) 104 to generate first information/signals and thentransmit radio signals including the first information/signals throughthe transceiver(s) 106. The processor(s) 102 may receive radio signalsincluding second information/signals through the transceiver 106 andthen store information obtained by processing the secondinformation/signals in the memory(s) 104. The memory(s) 104 may beconnected to the processor(s) 102 and may store a variety of informationrelated to operations of the processor(s) 102. For example, thememory(s) 104 may store software code including commands for performinga part or the entirety of processes controlled by the processor(s) 102or for performing the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.Herein, the processor(s) 102 and the memory(s) 104 may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) 106 may be connected to the processor(s) 102 andtransmit and/or receive radio signals through one or more antennas 108.Each of the transceiver(s) 106 may include a transmitter and/or areceiver. The transceiver(s) 106 may be interchangeably used with RadioFrequency (RF) unit(s). In the present disclosure, the wireless devicemay represent a communication modem/circuit/chip.

The second wireless device 200 may include at least one processor 202and at least one memory 204 and additionally further include at leastone transceiver 206 and/or one or more antennas 208. The processor(s)202 may control the memory(s) 204 and/or the transceiver(s) 206 and maybe configured to implement the descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument. For example, the processor(s) 202 may process informationwithin the memory(s) 204 to generate third information/signals and thentransmit radio signals including the third information/signals throughthe transceiver(s) 206. The processor(s) 202 may receive radio signalsincluding fourth information/signals through the transceiver(s) 206 andthen store information obtained by processing the fourthinformation/signals in the memory(s) 204. The memory(s) 204 may beconnected to the processor(s) 202 and may store a variety of informationrelated to operations of the processor(s) 202. For example, thememory(s) 204 may store software code including commands for performinga part or the entirety of processes controlled by the processor(s) 202or for performing the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.Herein, the processor(s) 202 and the memory(s) 204 may be a part of acommunication modem/circuit/chip designed to implement RAT (e.g., LTE orNR). The transceiver(s) 206 may be connected to the processor(s) 202 andtransmit and/or receive radio signals through one or more antennas 208.Each of the transceiver(s) 206 may include a transmitter and/or areceiver. The transceiver(s) 206 may be interchangeably used with RFunit(s). In the present disclosure, the wireless device may represent acommunication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 willbe described more specifically. One or more protocol layers may beimplemented by, without being limited to, one or more processors 102 and202. For example, the one or more processors 102 and 202 may implementone or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP,RRC, and SDAP). The one or more processors 102 and 202 may generate oneor more Protocol Data Units (PDUs) and/or one or more Service Data Unit(SDUs) according to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document. Theone or more processors 102 and 202 may generate messages, controlinformation, data, or information according to the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document. The one or more processors 102 and 202 maygenerate signals (e.g., baseband signals) including PDUs, SDUs,messages, control information, data, or information according to thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document and provide thegenerated signals to the one or more transceivers 106 and 206. The oneor more processors 102 and 202 may receive the signals (e.g., basebandsignals) from the one or more transceivers 106 and 206 and acquire thePDUs, SDUs, messages, control information, data, or informationaccording to the descriptions, functions, procedures, proposals,methods, and/or operational flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to ascontrollers, microcontrollers, microprocessors, or microcomputers. Theone or more processors 102 and 202 may be implemented by hardware,firmware, software, or a combination thereof. As an example, one or moreApplication Specific Integrated Circuits (ASICs), one or more DigitalSignal Processors (DSPs), one or more Digital Signal Processing Devices(DSPDs), one or more Programmable Logic Devices (PLDs), or one or moreField Programmable Gate Arrays (FPGAs) may be included in the one ormore processors 102 and 202. The descriptions, functions, procedures,proposals, methods, and/or operational flowcharts disclosed in thisdocument may be implemented using firmware or software and the firmwareor software may be configured to include the modules, procedures, orfunctions. Firmware or software configured to perform the descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be included in the one or more processors102 and 202 or stored in the one or more memories 104 and 204 so as tobe driven by the one or more processors 102 and 202. The descriptions,functions, procedures, proposals, methods, and/or operational flowchartsdisclosed in this document may be implemented using firmware or softwarein the form of code, commands, and/or a set of commands.

The one or more memories 104 and 204 may be connected to the one or moreprocessors 102 and 202 and store various types of data, signals,messages, information, programs, code, instructions, and/or commands.The one or more memories 104 and 204 may be configured by Read-OnlyMemories (ROMs), Random Access Memories (RAMs), Electrically ErasableProgrammable Read-Only Memories (EPROMs), flash memories, hard drives,registers, cash memories, computer-readable storage medium, and/orcombinations thereof. The one or more memories 104 and 204 may belocated at the interior and/or exterior of the one or more processors102 and 202. The one or more memories 104 and 204 may be connected tothe one or more processors 102 and 202 through various technologies suchas wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, controlinformation, and/or radio signals/channels, mentioned in the methodsand/or operational flowcharts of this document, to one or more otherdevices. The one or more transceivers 106 and 206 may receive user data,control information, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, from one or moreother devices. For example, the one or more transceivers 106 and 206 maybe connected to the one or more processors 102 and 202 and transmit andreceive radio signals. For example, the one or more processors 102 and202 may perform control so that the one or more transceivers 106 and 206may transmit user data, control information, or radio signals to one ormore other devices. The one or more processors 102 and 202 may performcontrol so that the one or more transceivers 106 and 206 may receiveuser data, control information, or radio signals from one or more otherdevices. The one or more transceivers 106 and 206 may be connected tothe one or more antennas 108 and 208 and the one or more transceivers106 and 206 may be configured to transmit and receive user data, controlinformation, and/or radio signals/channels, mentioned in thedescriptions, functions, procedures, proposals, methods, and/oroperational flowcharts disclosed in this document, through the one ormore antennas 108 and 208. In this document, the one or more antennasmay be a plurality of physical antennas or a plurality of logicalantennas (e.g., antenna ports). The one or more transceivers 106 and 206may convert received radio signals/channels etc. From RF band signalsinto baseband signals in order to process received user data, controlinformation, radio signals/channels, etc. Using the one or moreprocessors 102 and 202. The one or more transceivers 106 and 206 mayconvert the user data, control information, radio signals/channels, etc.Processed using the one or more processors 102 and 202 from the baseband signals into the RF band signals. To this end, the one or moretransceivers 106 and 206 may include (analog) oscillators and/orfilters.

Signal Processing Circuit Example to which Disclosure is Applied

FIG. 24 illustrates a signal processing circuit for a transmit signal.

Referring to FIG. 24 , a signal processing circuit 1000 may include ascrambler 1010, a modulator 1020, a layer mapper 1030, a precoder 1040,a resource mapper 1050, and a signal generator 1060. Although notlimited thereto, an operation/function of FIG. 24 may be performed bythe processors 102 and 202 and/or the transceivers 106 and 206 of FIG.23 . Hardware elements of FIG. 24 may be implemented in the processors102 and 202 and/or the transceivers 106 and 206 of FIG. 23 . Forexample, blocks 1010 to 1060 may be implemented in the processors 102and 202 of FIG. 23 . Further, blocks 1010 to 1050 may be implemented inthe processors 102 and 202 of FIG. 23 and the block 1060 of FIG. 23 andthe block 2060 may be implemented in the transceivers 106 and 206 ofFIG. 23 .

A codeword may be transformed into a radio signal via the signalprocessing circuit 1000 of FIG. 24 . Here, the codeword is an encodedbit sequence of an information block. The information block may includetransport blocks (e.g., a UL-SCH transport block and a DL-SCH transportblock). The radio signal may be transmitted through various physicalchannels (e.g., PUSCH and PDSCH).

Specifically, the codeword may be transformed into a bit sequencescrambled by the scrambler 1010. A scramble sequence used for scramblingmay be generated based on an initialization value and the initializationvalue may include ID information of a wireless device. The scrambled bitsequence may be modulated into a modulated symbol sequence by themodulator 1020. A modulation scheme may include pi/2-BPSK(pi/2-BinaryPhase Shift Keying), m-PSK(m-Phase Shift Keying), m-QAM(m-QuadratureAmplitude Modulation), etc. A complex modulated symbol sequence may bemapped to one or more transport layers by the layer mapper 1030.Modulated symbols of each transport layer may be mapped to acorresponding antenna port(s) by the precoder 1040 (precoding). Output zof the precoder 1040 may be obtained by multiplying output y of thelayer mapper 1030 by precoding matrix W of N*M. Here, N represents thenumber of antenna ports and M represents the number of transport layers.Here, the precoder 1040 may perform precoding after performing transformprecoding (e.g., DFT transform) for complex modulated symbols. Further,the precoder 1040 may perform the precoding without performing thetransform precoding.

The resource mapper 1050 may map the modulated symbols of each antennaport to a time-frequency resource. The time-frequency resource mayinclude a plurality of symbols (e.g., CP-OFDMA symbol and DFT-s-OFDMAsymbol) in a time domain and include a plurality of subcarriers in afrequency domain. The signal generator 1060 may generate the radiosignal from the mapped modulated symbols and the generated radio signalmay be transmitted to another device through each antenna. To this end,the signal generator 1060 may include an Inverse Fast Fourier Transform(IFFT) module, a Cyclic Prefix (CP) inserter, a Digital-to-AnalogConverter (DAC), a frequency uplink converter, and the like.

A signal processing process for a receive signal in the wireless devicemay be configured in the reverse of the signal processing process (1010to 1060) of FIG. 24 . For example, the wireless device (e.g., 100 or 200of FIG. 23 ) may receive the radio signal from the outside through theantenna port/transceiver. The received radio signal may be transformedinto a baseband signal through a signal reconstructer. To this end, thesignal reconstructer may include a frequency downlink converter, ananalog-to-digital converter (ADC), a CP remover, and a Fast FourierTransform (FFT) module. Thereafter, the baseband signal may bereconstructed into the codeword through a resource de-mapper process, apostcoding process, a demodulation process, and a de-scrambling process.The codeword may be reconstructed into an original information block viadecoding. Accordingly, a signal processing circuit (not illustrated) forthe receive signal may include a signal reconstructer, a resourcedemapper, a postcoder, a demodulator, a descrambler, and a decoder.

Example of a Wireless Device Applied to the Present Disclosure

FIG. 25 illustrates another example of a wireless device applied to thepresent disclosure. The wireless device may be implemented in variousforms according to a use-case/service (see FIG. 22 ).

Referring to FIG. 25 , wireless devices 1010 and 1020 may correspond tothe wireless devices 100 and 200 of FIG. 23 and may be configured byvarious elements, components, units/portions, and/or modules. Forexample, each of the wireless devices 1010 and 2010 may include acommunication unit 110, a control unit 120, a memory unit 130, andadditional components 140. The communication unit may include acommunication circuit 112 and transceiver(s) 114. For example, thecommunication circuit 112 may include the one or more processors 102 and202 and/or the one or more memories 104 and 104 of FIG. 23 . Forexample, the transceiver(s) 114 may include the one or more transceivers106 and 106 and/or the one or more antennas 108 and 108 of FIG. 23 . Thecontrol unit 120 is electrically connected to the communication unit110, the memory 130, and the additional components 140 and controlsoverall operation of the wireless devices. For example, the control unit120 may control an electric/mechanical operation of the wireless devicebased on programs/code/commands/information stored in the memory unit130. The control unit 120 may transmit the information stored in thememory unit 130 to the exterior (e.g., other communication devices) viathe communication unit 110 through a wireless/wired interface or store,in the memory unit 130, information received through the wireless/wiredinterface from the exterior (e.g., other communication devices) via thecommunication unit 110).

The additional components 140 may be variously configured according totypes of wireless devices. For example, the additional components 140may include at least one of a power unit/battery, input/output (I/O)unit, a driving unit, and a computing unit. The wireless device may beimplemented in the form of, without being limited to, the robot (1010 aof FIG. 22 ), the vehicles (1010 b-1 and 1010 b-2 of FIG. 22 ), the XRdevice (1010 c of FIG. 22 ), the hand-held device (1010 d of FIG. 22 ),the home appliance (1010 e of FIG. 22 ), the IoT device (1010 f of FIG.22 ), a digital broadcast terminal, a hologram device, a public safetydevice, an MTC device, a medicine device, a fintech device (or a financedevice), a security device, a climate/environment device, the AIserver/device (400 of FIG. 22 ), the BSs (1020 of FIG. 22 ), a networknode, etc. The wireless device may be used in a mobile or fixed placeaccording to a use-example/service.

In FIG. 23 , the entirety of the various elements, components,units/portions, and/or modules in the wireless devices 100 and 100 maybe connected to each other through a wired interface or at least a partthereof may be wirelessly connected through the communication unit 110.For example, in each of the wireless devices 100 and 100, the controlunit 120 and the communication unit 110 may be connected by wire and thecontrol unit 120 and first units (e.g., 130 and 140) may be wirelesslyconnected through the communication unit 110. Each element, component,unit/portion, and/or module within the wireless devices 100 and 100 mayfurther include one or more elements. For example, the control unit 120may be configured by a set of one or more processors. As an example, thecontrol unit 120 may be configured by a set of a communication controlprocessor, an application processor, an Electronic Control Unit (ECU), agraphical processing unit, and a memory control processor. As anotherexample, the memory 130 may be configured by a Random Access Memory(RAM), a Dynamic RAM (DRAM), a Read Only Memory (ROM)), a flash memory,a volatile memory, a non-volatile memory, and/or a combination thereof.

Portable Device Example to which Disclosure is Applied

FIG. 26 illustrates a portable device applied to the present disclosure.The portable device may include a smart phone, a smart pad, a wearabledevice (e.g., a smart watch, a smart glass), and a portable computer(e.g., a notebook, etc.). The portable device may be referred to as aMobile Station (MS), a user terminal (UT), a Mobile Subscriber Station(MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), or aWireless terminal (WT).

Referring to FIG. 26 , a portable device 1010 may include an antennaunit 108, a communication unit 110, a control unit 120, a memory unit130, a power supply unit 140 a, an interface unit 140 b, and aninput/output unit 140 c. The antenna unit 108 may be configured as apart of the communication unit 110. The blocks 110 to 130/140 a to 140 ccorrespond to the blocks 110 to 130/140 of FIG. 25 , respectively.

The communication unit 110 may transmit/receive a signal (e.g., data, acontrol signal, etc.) to/from another wireless device and eNBs. Thecontrol unit 120 may perform various operations by controllingcomponents of the portable device 1010. The control unit 120 may includean Application Processor (AP). The memory unit 130 may storedata/parameters/programs/codes/instructions required for driving theportable device 1010. Further, the memory unit 130 may storeinput/output data/information, etc. The power supply unit 140 a maysupply power to the portable device 1010 and include a wired/wirelesscharging circuit, a battery, and the like. The interface unit 140 b maysupport a connection between the portable device 1010 and anotherexternal device. The interface unit 140 b may include various ports(e.g., an audio input/output port, a video input/output port) for theconnection with the external device. The input/output unit 140 c mayreceive or output a video information/signal, an audioinformation/signal, data, and/or information input from a user. Theinput/output unit 140 c may include a camera, a microphone, a user inputunit, a display unit 140 d, a speaker, and/or a haptic module.

As one example, in the case of data communication, the input/output unit140 c may acquire information/signal (e.g., touch, text, voice, image,and video) input from the user and the acquired information/signal maybe stored in the memory unit 130. The communication unit 110 maytransform the information/signal stored in the memory into the radiosignal and directly transmit the radio signal to another wireless deviceor transmit the radio signal to the eNB. Further, the communication unit110 may receive the radio signal from another wireless device or eNB andthen reconstruct the received radio signal into originalinformation/signal. The reconstructed information/signal may be storedin the memory unit 130 and then output in various forms (e.g., text,voice, image, video, haptic) through the input/output unit 140 c.

Here, wireless communication technology implemented in wireless devices100 and 200 of the present disclosure may include Narrowband Internet ofThings for low-power communication in addition to LTE, NR, and 6G. Inthis case, for example, NB-IoT technology may be an example of Low PowerWide Area Network (LPWAN) technology and may be implemented as standardssuch as LTE Cat NBT, and/or LTE Cat NB2, and is not limited to the namedescribed above. Additionally or alternatively, the wirelesscommunication technology implemented in the wireless devices 100 and 200of the present disclosure may perform communication based on LTE-Mtechnology. In this case, as an example, the LTE-M technology may be anexample of the LPWAN and may be called various names including enhancedMachine Type Communication (eMTC), and the like. For example, the LTE-Mtechnology may be implemented as at least any one of various standardssuch as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BandwidthLimited (non-BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and/or7) LTE M. Additionally or alternatively, the wireless communicationtechnology implemented in the wireless devices 100 and 200 of thepresent disclosure may includes at least one of ZigBee, Bluetooth, andLow Power Wide Area Network (LPWAN) considering the low-powercommunication, and is not limited to the name described above. As anexample, the ZigBee technology may generate personal area networks (PAN)associated with small/low-power digital communication based on variousstandards including IEEE 802.15.4, and the like, and may be calledvarious names.

The embodiments described above are implemented by combinations ofcomponents and features of the present disclosure in predeterminedforms. Each component or feature should be considered selectively unlessspecified separately. Each component or feature may be carried outwithout being combined with another component or feature. Moreover, somecomponents and/or features are combined with each other and mayimplement embodiments of the present disclosure. The order of operationsdescribed in embodiments of the present disclosure may be changed. Somecomponents or features of one embodiment may be included in anotherembodiment, or may be replaced by corresponding components or featuresof another embodiment. It is apparent that some claims referring tospecific claims may be combined with another claims referring to theclaims other than the specific claims to constitute the embodiment oradd new claims by means of amendment after the application is filed.

Embodiments of the present disclosure may be implemented by variousmeans, for example, hardware, firmware, software, or combinationsthereof. When embodiments are implemented by hardware, one embodiment ofthe present disclosure may be implemented by one or more applicationspecific integrated circuits (ASICs), digital signal processors (DSPs),digital signal processing devices (DSPDs), programmable logic devices(PLDs), field programmable gate arrays (FPGAs), processors, controllers,microcontrollers, microprocessors, and the like.

When embodiments are implemented by firmware or software, one embodimentof the present disclosure may be implemented by modules, procedures,functions, etc. Performing functions or operations described above.Software code may be stored in a memory and may be driven by aprocessor. The memory is provided inside or outside the processor andmay exchange data with the processor by various well-known means.

It is apparent to those skilled in the art that the present disclosuremay be embodied in other specific forms without departing from essentialfeatures of the present disclosure. Accordingly, the aforementioneddetailed description should not be construed as limiting in all aspectsand should be considered as illustrative. The scope of the presentdisclosure should be determined by rational construing of the appendedclaims, and all modifications within an equivalent scope of the presentdisclosure are included in the scope of the present disclosure.

Although a method of transmitting and receiving a PTRS in a wirelesscommunication system according to the present disclosure has beendescribed focusing on examples applying to 3GPP LTE/LTE-A system and 5Gsystem (new RAT system), the method can also be applied to other variouswireless communication systems.

The invention claimed is:
 1. A method of receiving, by a user equipment(UE), a phase tracking reference signal (PTRS) in a wirelesscommunication system, the method comprising: receiving configurationinformation for Physical Downlink Shared Channel (PDSCH), wherein theconfiguration information includes configurations for a plurality ofTransmission Configuration Indication states (TCI states), and each TCIstate includes parameters for configuring a quasi-co-location (QCL)relationship between a reference signal and the PDSCH; receiving PTRSconfiguration information, wherein the PTRS configuration informationincludes information for a frequency density of the PTRS that includes afirst threshold and a second threshold; receiving an activation command,wherein, based on the activation command, one or more TCI states amongthe plurality of TCI states are mapped to codepoints of TCI field;receiving downlink control information (DCI) for scheduling of thePDSCH, wherein the DCI includes the TCI field; and receiving the PDSCHand the PTRS, based on the DCI, wherein the DCI is a single DCI and theTCI field represents a codepoint to which two TCI states are mapped,wherein, based on a frequency domain resource related to a first TCIstate not overlapping with a frequency domain resource related to asecond TCI state in a frequency resource region assigned based on thesingle DCI: i) the frequency density of the PTRS is determined for eachof the two TCI states, and ii) the frequency density of the PTRS isdetermined based on comparing (i) a number of resource blocks related toeach of the two TCI states in the frequency resource region assignedbased on the single DCI and (ii) at least one of the first threshold orthe second threshold.
 2. The method of claim 1, wherein each of thefirst threshold and the second threshold is set as a plurality ofvalues.
 3. The method of claim 1, wherein the DCI includes a frequencyresource assignment field, and wherein the plurality of TCI states basedon the TCI field are mapped to the frequency resource region assignedbased on the frequency resource assignment field.
 4. The method of claim3, wherein the assigned frequency resource region includes a firstregion and a second region that do not overlap in a frequency domain,and wherein the first region is related to the first TCI state, and asecond region is related to the second TCI state.
 5. The method of claim4, wherein the assigned frequency resource region includes i) the firstregion including an even-numbered precoding resource block group (PRG)and ii) the second region including an odd-numbered PRG.
 6. The methodof claim 4, wherein the assigned frequency resource region is dividedinto the first region and the second region that do not overlap, basedon a ceiling function.
 7. The method of claim 4, wherein a firstfrequency density of the PTRS is determined based on a number ofresource blocks of the first region, and wherein a second frequencydensity of the PTRS is determined based on a number of resource blocksof the second region.
 8. The method of claim 7, wherein, in the firstregion, the PTRS is mapped to a resource element based on the firstfrequency density, and wherein, in the second region, the PTRS is mappedto a resource element based on the second frequency density.
 9. Themethod of claim 1, wherein the DCI includes an antenna port field, andwherein DM-RS ports of the same CDM group are indicated based on theantenna port field.
 10. A user equipment (UE) receiving a phase trackingreference signal (PTRS) in a wireless communication system, the UEcomprising: one or more transceivers; one or more processors; and one ormore memories configured to store instructions for operations executedby the one or more processors, the one or more memories being connectedto the one or more processors, wherein the operations comprise:receiving configuration information for Physical Downlink Shared Channel(PDSCH), wherein the configuration information includes configurationsfor a plurality of Transmission Configuration Indication states (TCIstates), and each TCI state includes parameters for configuring aquasi-co-location (QCL) relationship between a reference signal and thePDSCH; receiving PTRS configuration information, wherein the PTRSconfiguration information includes information for a frequency densityof the PTRS that includes a first threshold and a second threshold;receiving an activation command, wherein, based on the activationcommand, one or more TCI states among the plurality of TCI states aremapped to codepoints of TCI field; receiving downlink controlinformation (DCI) for scheduling of the PDSCH; wherein the DCI includesthe TCI field; and receiving the PDSCH and the PTRS, based on the DCI,wherein the DCI is a single DCI and the TCI field represents a codepointto which two TCI states are mapped, wherein, based on a frequency domainrelated to a first TCI state not overlapping with a frequency domainresource related to a second TCI state in a frequency resource regionassigned based on the single DCI: i) the frequency density of the PTRSis determined for each of the two TCI states, and ii) the frequencydensity of the PTRS is determined based on comparing (i) a number ofresource blocks related to each of the two TCI states in the frequencyresource region assigned based on the single DCI and (ii) at least oneof the first threshold or the second threshold.
 11. The UE of claim 10,wherein the DCI includes a frequency resource assignment field, andwherein the plurality of TCI states based on the TCI field are mapped tothe frequency resource region assigned based on the frequency resourceassignment field.
 12. The UE of claim 11, wherein the assigned frequencyresource region includes a first region and a second region that do notoverlap in a frequency domain, and wherein the first region is relatedto the first TCI state, and a second region is related to the second TCIstate.
 13. The UE of claim 12, wherein a first frequency density of thePTRS is determined based on a number of resource blocks of the firstregion, and wherein a second frequency density of the PTRS is determinedbased on a number of resource blocks of the second region.
 14. The UE ofclaim 13, wherein, in the first region, the PTRS is mapped to a resourceelement based on the first frequency density, and wherein, in the secondregion, the PTRS is mapped to a resource element based on the secondfrequency density.
 15. A method of transmitting, by a base station (BS),a phase tracking reference signal (PTRS) in a wireless communicationsystem, the method comprising: transmitting, to a user equipment (UE),configuration information for Physical Downlink Shared Channel (PDSCH),wherein the configuration information includes configurations for aplurality of Transmission Configuration Indication states (TCI states),and each TCI state includes parameters for configuring aquasi-co-location (QCL) relationship between a reference signal and thePDSCH; transmitting, to the UE, PTRS configuration information, whereinthe PTRS configuration information includes information for a frequencydensity of the PTRS that includes a first threshold and a secondthreshold; transmitting, to the UE, an activation command, wherein,based on the activation command, one or more TCI states among theplurality of TCI states are mapped to codepoints of TCI field;transmitting, to the UE, downlink control information (DCI) forscheduling of the PDSCH; wherein the DCI includes the TCI field; andtransmitting, to the UE, the PDSCH and the PTRS, based on the DCI,wherein the DCI is a single DCI and the TCI field represents a codepointto which two TCI states are mapped, wherein, based on a frequency domainrelated to a first TCI state not overlapping with a frequency domainresource related to a second TCI state in a frequency resource regionassigned based on the single DCI: i) the frequency density of the PTRSis determined for each of the two TCI states, and ii) the frequencydensity of the PTRS is determined based on comparing (i) a number ofresource blocks related to each of the two TCI states in the frequencyresource region assigned based on the single DCI and (ii) at least oneof the first threshold or the second threshold.